Out of curiosity: What's Intellectus?

It's discussed on YS292 in the Places of Power section.  In brief, it's the ability to simply know everything about a place. 

Sure, and they may well tag/invoke those aspects to reflect their advantage. 

However your capitalization of "Ambush action" made me think you were discussing the Ambush trapping under Stealth.  It would only apply to the first recognizably hostile act...which is probably when things go dark. 

Good point on two triggers...I somehow overlooked the "biped" criteria   

If characters are Blind & Deaf as a taggable aspect, is it fair to then tag that as part of an Ambush action? 

They're certainly taggable as part of an attack.  It'll be situational, but I suspect using them as part of a Stealth Ambush would be difficult.  Going suddenly deaf and blind should be a big clue that someone who dislikes me is nearby...

I'd suggest using the aspects for compels instead anyway.  You're not going to use ranged attacks if you can't sense anything at range. 

The skill descriptions define how they're used...so it depends on context.  Someone shoots at you - you probably dodge with Athletics.  But what if you're driving a car?  Athletics no longer makes sense.  Action instigates the reaction, it will almost always have the primary say in what gets used simply because it is proactive.  But, sometimes, you can add a twist to the narrative and change things...

First - would you agree that the selection of Water as Channeling-element for a Biomancer-growing-toward-wizard?

Sure.  You can make an argument for any of the Grecian elements fitting once you start digging into each element's purported mystical attributes.  But Water is often closely related to healing.

Second - what would you say of these effects:

• Effects similar to tear gas by causing mucus membranes in the eyes, nose and mouth to overproduce? (Maneuver: Aspect "Tear gas" or similar on the target)
• Choking/suffocation from water in the lungs, exuded blood & mucus? (Attack)

Those can work. 

Or would these be too complex for Evocation? I'm still really on the fence. I really like them, but the might very well need Biomancy Evothaum.

It's all in how you describe it.  "Infusing the flesh with excess water." is simple evocation.  "Combining appropriate molecules to create tear gas." is complex, should require a knowledge of chemistry, and is probably thaumaturgy.  But both may well have the same result of difficulty seeing and breathing. 

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Regarding magical healing, I tend towards the following:  Any kind of instant healing needs some amount of medical knowledge* however anyone can enhance a body's natural healing ability. 

*The medical knowledge doesn't have to be the caster's.  A victim could get a broken arm set and splinted at the hospital before having a mage speed the healing.  You just don't want to speed the healing before having the arm set unless you have the medical knowledge to ensure it heals correctly. 

That would be a 2400 mile hike for me.    I do have a few cheat sheets you're welcome to, PM me if you want 'em.

Is there a step by step walkthrough of how to create your character? 

Here's a very basic outline listed in the order presented and numbered in the order I often use:
 - (1) Come up with some idea / concept.
 - (4) Choose a template.
 - Create your aspects:
 - - (2) High Concept
 - - (5) Trouble
 - - (7) Phases
 - (6) Choose your Skills.
 - (3) Choose any Powers.
The phase aspects are typically done as a group so it makes sense to put them last.  The order, in general, isn't going to be strict either.  If I have aspect ideas I'll note them and if concepts change things will get modified to fit...or vice versa.  Powers and Templates are often done in concert - makes getting any 'musts' easier.  Everyone will have their own preferences, this simply made it easier for me. 

For the Stunts and Powers:
Inhuman Recovery -2 (Catch: 0, just general constant recovery)
Inhuman Toughness -2 (Catch: 0, again, just general amped up toughness)
Supernatural Strength -4 (forgot if there was a catch on this, I didn't write one down though)
Marked by Power -1
Item of Power +1 (With the Channeling -2 bonus) ***Not even sure if this needs to go here***

So with this do I have -8, or does the Channeling add into it and go over my point allotment?

Recovery and Toughness powers must have a Catch.  Usually the catch will be worth a rebate and save you some points. 

I'd be leery of putting Channeling into an Item of Power, mostly because spellcasting is extremely skill dependent.  Doesn't really make sense unless you've come up with a unique background twist.    Items of Power do count towards your refresh.

Also, how do you go about picking stunts?  The book was very thorough on what they do, but not how many you are allowed to pick or how many points they cost, if any.  Do they just inherently come with your skills?  Say I wanted the "Wall of Death" stunt, would I have to give up other powers?

Stunts cost 1 refresh each so you'll need to pay for them.  Generally you'll only have one or two with other refresh being put in powers or saved for fate points. 

Character Items:  How does this work?  Do you just state "My character has this weapon, this piece of clothing..."?  If they have 'extras' like imbued powers how do you go about that?

Are you talking about magical items or mundane equipment?  The former you pay for with refresh and need to meet your high concept.  The latter are going to be a combination of what makes sense for the character to have and your Resource level.  If you have focus or enchanted items (granted by spellcasting powers) you'll choose what they are or leave a few as empty potion slots.

I just followed the pyramid pattern on Dresden's sample sheet, but I've seen a few posted characters on here don't follow that.  Are there multiple ways/rules of doing this?

You've got 35 points in skills - that meet the cap you're starting at?  There are multiple ways, the general rule is "You cannot have more skills at a higher level than you have at each and every lower level."

Consequences...

Consequences are your health...sort of.  In any case the only thing you need to know about them during character creation is how many you have.  That's going to be one each of Mild, Moderate, Severe, and Extreme unless you have skills, stunts, or powers granting you extra.