Its not a case of imagination, its a case of will.  If you will it not hurt anyone, then you can't perform a magic effect designed to hurt people. 

That's blatantly not the case.  Many, many times Harry talks about how fire and other natural effects will behave naturally once created.  Will allows you to control them better.  Clearly if they behave naturally (and we see this all over the place), a lack of control could easily cause a death by magic.  The characters just luck out since the D-verse doesn't seem to have friendly fire.

The theory is:

Most people who kill someone with a gun do it on reflex, or because they were under orders, or to save their own life, or even in pursuit of righteous vengeance. They do it without focusing their entire will and being onto the idea that this guy needs to die and nothing else. by believing in his death so hard it happens

Even one of the books mentions how this isn't the case.  Green soldiers can hit targets well, but they almost always suck at hitting people.  They unconsciously avoid it.  It takes will and a decision to do it most times.

I don't see how it is all that different with magic anyhow.  You toss a fireball at someone you aren't thinking "kill, kill, kill" necessarily.  You could just be thinking "fire, fire fire" or "get him away" or "make him stop" or any number of things (maybe even that he isn't human).  Even thoughts like that will come as a reflex in time.

"Potions" seem to clearly be intended for one-use items of all types, given the hanky example.

Overall I'd say the Laws of Magic in the Dresden-verse are a little over-the-top in a "it's a bit artificial" kind of way.

That said, I think as far as the game is concerned they are meant to be there more to balance the game than anything else.  Altering and reading minds is insanely powerful, heck even Mind Tricks in Star Wars games are pretty darn awesome and the D-verse allows much larger effects.  I don't think anyone can argue that messing with undead isn't also very potent.  Same goes with time travel.  The Outer Gates bit is, I think, largely meant to be on a plot level (though personally I feel that the "researching" bit should just be a legal measure and not a game mechanic, depends on how heavy the GM wants the plot device).  So Lawbreaker for all that makes sense from a purely game balance and plot perspective.

That leaves transforming and killing.  Now, some transforming seems a bit silly to count as a lawbreaker, to me.  If you are repairing tissue damage, removing scares, or a little cosmetic surgery, then that seems rather silly to slap lawbreaker on it (certainly over the top from a game balance perspective).  If you are doing something that alters/destroys the mind, then that goes largely into the area of the first law.  (Augmentation beyond a normal human could be considered similarly, or just on a game balance level as OP if you don't restrict it in some way).  That brings us to the first law, which is a bit murky.  Killing someone with magic.  Now, from a purely RP perspective, killing someone with magic and normally seems about the same to me.  If you purposefully incinerate someone with magic, you have to BELIEVE magic can be used to kill and that they should die.  If you knowingly shoot to kill someone, then that's really no different, honestly.  Seems a bit odd for the game to make a difference though.  On the other hand, magic can be crazy-powerful, hitting huge areas and killing people from far, far away that couldn't otherwise be killed.  Lawbreaker helps keep it under control if humans or sufficiently human-like creatures are around.

Of course, to go to the OP's original concern, I think there is something more interesting afoot from a different perspective.  Presumably, if a non-mortal kills someone with magic, they don't change because they don't have any choice in the matter; it is merely part of their nature.  On the other hand, I find it more odd the other way around.  Harry can kill talking things with magic, things that can think and learn (yet can't change their nature somehow), and that's OK.  Seems a bit screwed up to me if killing people is problematic.  Something is really off with those ethics.

In the end, I think you have to take the power of magic and the universe and just consider magic to have very special rules.  Magic alters you more easily and changes you more easily.  These changes are overreactions to what you are doing compared to how it would work if you did it any other way.  That's why you can't be a wizard-psychiatrist or bring a recently dead loved one back to life whereas if you could do it with science it would be OK (you don't see behavioral therapists or doctors turning into monsters)*.

*Worst case you get surgeons who are egotistical jerks, really, well, beyond the people who are monsters for other reasons.

+1 for researchable is more than reasonable. You could even go to +2, but I like to take the fact into account that people need to realize what you are before they can search for your weakness. And norse-myth Nature is not something that's blatantly obvious.\

Faeries are often far from obvious.  Distinguishing a demon from an Outsider or even some Fae isn't necessarily an easy thing either.  If we're talking about PCs, then they are all going to look pretty human.  If we're worried about the game effect, then I don't think a guy running around with a hammer and some lightning effects makes it THAT hard to guess.  Anyhow, it is certainly no harder than figuring out someone like Kincaid is a demon.  Yeah, some guys with a catch ARE easy to spot, but a lot of them aren't, as the books demonstrate many times.

Naw, Holy or Mistltoe are definitely +3 or even +4.

Research isn't THAT tough.  It's a little harder than cold iron for Fae (though probably about the same difficulty as realizing cold iron = iron in any form).  Certainly doesn't require access to any remotely hard-to-get books.  Heck, you can google it, and in the Dresden-verse it would probably be a bit easier since the creatures actually exist (which means more lore).  So that's +1 or +2.

Access is also done in very general terms.  The +1 is for VERY rare stuff like true magic, and any plant an average person would know the name of is not that.  Iron is a bit easier to get, but it isn't hard to get mistletoe, plenty of shops sell it.  Definitely not something that's "only a rare class of people in the world have".  This one actually makes me lean towards +2 for Research as well when you think of the difference in scope between +1 and +2 for research "relatively easy to get" vs. "very hard" (and the third category in both is "almost impossible.").

These are very wide categories, one has to remember.

Well, I was messing around with a bunch of ideas in my head and decided I wanted to see about making a Thor-like character.  I think having him be Thor's son who largely wants to follow in Thor's footsteps, so to speak (e.g. thunder and lightning, hammer, fighting bad guys, but not copying his dad's deeds).  For the purposes of the character, Thor is angelspawn of some sort (like the OW says most gods are), and a good guy who lives in the Nevernever.  I think my character will have grown up in the Nevernever for a significant amount of time (I want to use "thees" and "thous" without my guy doing it as a fad).  He's NOT an Emissary of the Asgard/Thor though, (Thor wants him to make his own way, but that doesn't mean his dad never asks for a favor...like any relative might).

Obviously the high concept is "Son of Thor".  Right now I am mostly thinking about two issues.  First, what's his trouble?  I've thought of Like his Father before him (e.g. wants to be like dad), One of the Asgard (e.g. their enemies are his enemies and other such things), and "I am the Son of Thor!" (really dislikes concealing his identity).  Anyone have other ideas?

Also, Toughness and perhaps Recovery powers make some sense, but what would his catch be?  I have trouble thinking of something that makes a lot of sense here, best thing I got is "Unholy Power" such as hellfire, unholy water, etc, but that seems far from perfect.  Any thoughts there?

I'm pretty early in the creative stages, obviously, but I thought some people might have some neat ideas to share, so share away!