1) How many kits (rough estimate) would you say you buy in a year?
Hard to say... I binge-buy when the mood or subject interest hits me, but the December sales are when I run up the score...
2) Do you buy a kit as soon as it is released or do you wait a while? If you wait, what's the main reason for waiting?
If it's something I want right now, then I'll buy it as it is available. Waiting means it is pre-ordered.
3) Do you buy online or from a physical LHS or show vendors or combination?
Yes. I travel several times a year and always try support a LHS whenever I can, but online is where I spend most of my $$. My LHS is OK for consumables. but not so much for kit selection. The best brick and mortar LHS I've found were in Pittsburgh, PA and in Columbus, OH.
4) If you buy online, from who? (feel free to list more than one if you have multiple favorites)
Great Models and Squadron get the bulk of my money, but I've also used InternetHobbies, Hannants, Aviapress and god knows who else to find what I'm looking for.