I think that the WC is trying to balance out their place between two worlds, the mortal and the supernatural.

I think it more about finding themselves less relevant in a modern world, the time of the village wise woman or man has past.   Kids who show signs of talent no longer have any place to go or any knowledge of what it all means.  All they know is they have these cool talents and like normal kids everywhere they experiment with them and get into trouble.  Meanwhile the WC has been decimated by wars over the last thousand years and have spent their time navel gazing unlike Harry who has attempted to fit into the modern world openly as a practicing wizard.   As a result, zero tolerance has evolved into not just being the safest course for both worlds but the easiest to implement.  But as we all know zero tolerance policies are seriously flawed because there isn't a one size fits all and justice usually isn't served by it... But those those who advocate it will argue, it keeps everyone safe so it doesn't matter that perhaps a few talented babies who might make great wizards someday are thrown out with the bath water.

That's really interesting. Any particular actions? Her particular malice toward Dresden, that's later pretty much gone entirely after Small Favor, does seem pretty out of place. It's handwaved when she says she was trying to protect him, or that she was showing him tough love, or that she's a changeable Fae and can do what she wants (pretty much variably at later points in the series), but it still sticks out pretty far to me.

Which makes me think that she was trying all along to resist the infection..  On one hand she was trying to undermine Mab, that is why she wanted the Knife to begin with, power..  At the same time she did her best to save Harry, perhaps her promise to Margaret in this case was stronger than the infection... But remember in Proven Guilty one minute she was warning Harry that she must not be let go, then the next wanting him to turn her lose. 

Yeah.....

I am rereading the series, but not all at once...  My last reread was Grave Peril which was fascinating considering what we know now...   

This feels like a comment that Jim would laugh at.....

Why?   If Harry's job is done, he either will  die or get his reward... 

It may be if Maggie saw the two options available to Thomas, her son, and chose her needs for him over the chance for him to have a happy, normal life.

 Thing is, Thomas was screwed from the get go...   His life would never be "normal" whether she took him with her or not. 
Lord Raith would forever be out to kill him along with her for starters, that doesn't make for a normal life.  He still would have to deal with the demon inside of him.   He may never have met Justine..

   I thought it was established that she was between 135 and 150 when she died..  For a wizard that would be like a human in her early thirties...

I don't know that she was excessively powerful in of itself, but she made trouble for herself and the Council because she colored outside of the lines.  When they jumped her for it it escalated from there as she upped her rebellion against the system and yeah, she did commit real crimes... As Chauncy said, they were getting ready to welcome her, but she met Malcolm and turned her life around.