crap.... now i feel like i need to update that to actually answer your questions.
i think a lot of people carry them cross leg.. right handed goes left leg and vv.
That way your weak hand pulls up your pant leg while the guy kicks you in the face, and maybe misses and you end up with your strong hand on the weapon. and.. usually they face in the direction your hand will be if you try to grab for it. if you have to contort and twist your arm, it's wrong... i.e. butt goes towards your butt. barrel down.. you can also do same side on outside of your leg... butt to butt still applies. but then you have to move your pant leg AND remove the gun without snagging it with the same hand usually.
or you can do 4 guns, one on either side of your leg per both legs... just watch how you walk or they may spark and create forest fires while you're walking.
as for weapons, i personally don't see any use in any weapon less than a .380 with the best hollow points on the mkt, which is hotly debated, i prefer gold dot ammo, i've never had a misfire or dud and they have incredible penetration even at .380.
i like the ruger LCP because it is small, and THIN... it will fit anywhere, especially on your ankle.
i personally don't recommend revolvers either because you are limited on ammo, and unless you practice a lot and have a speed loader, it's difficult to reload, especially not as quickly as with a semi auto. sure, some people can do it, but, i can't. so i don't. plus, you have more rounds. LCP has up to a 10rd extended mag, which means 11 shots. vs 4,5,6 in a cute little revolver - when whoever you're up against most likely recently acquired your neighbor's glock.....
also, barrel size is somewhat intimidating too. a large guy may look at a 22 and laugh at you. at least a .380 with gold dot will do the job even for an obese attacker. 9mm is preferred, 45, is probably most preferred, though there is a lot of debate about this too as it usually has to do with the specific ammo you're shooting. but specifically, i personally would go with the LCP because of it's size and apparent reliability.
but in general, i've been looking more into compacts rather than sub compacts, they tend to have less snap and be more accurate. though i can hit a tight group with my lcp. i have a lot of practice on it and know the proper way to hold it so it isn't so snappy like most people report it as being.
I would point out that, if an attacker is close enough to kick you when drawing from an ankle holster, he's probably close enough to punch you if you draw from anywhere else. Maybe some empty-hand skills or a distraction would be in order....