I think you will find warping to be no bigger an issue than you have had in the past. I've found AEB-L warps less than some of the other stainless I've tried. I've started milling my primary bevels all the way down to 20 thou and that's when I've had to work more on watching out for warping during HT.
As far as the milling goes. I've recently switched to flood coolant. It likes flood coolant. Had a lot fewer issues with burs after the switch. It also really likes sharp tools (obviously right). Not as bad as titanium but same situation. When an endmill is too dull for titanium I can usually still get at least one knife blade out of AEB-L. It becomes very apparent when its time to switch an endmill out. And yes I only use carbide. It is MUCH easier to work with than S30V. That's good and bad I guess. As I'm sure you are aware (but for the sake of others that might be reading this thread) its not nearly as wear resistant as S30V. But it take an edge (and a sharper edge) very quick and easy. My experience is that the average person has a tough time sharpening a S30V blade, and field sharpening S30V is tough even for an experienced user...sorry I'm getting side tracked on the virtues of AEB-L
When I get my feeds and speeds dialed in and my fixture is ridged the finishes look fantastic. I buy all my AEB-L from the Steel Baron in NJ. Its does not appear to vary, very much from lot to lot. I've not found hardened spots, or at least if I have I've not noticed.
I ream all my holes 3/16 before HT. After HT I run some 400-600 grit sandpaper in them to remove any decarb or scale. After a quick sanding the 3/16 pins appear to fit that same as the did before HT.
I've tried to be accurate with my comments but take them all with a grain of salt as I'm still very much a novice when it comes to machining. Hope to have added at least some value though.