Traveller,
I'll try to answer some of your questions. The 15 to 20 degree slant is a little faster and more natural and is considered a bit more competitive, but not very period. Some folks like a cross draw for looks and function, but there is the risk of breaking the 170, and the dance, that is why a lot of shooters have gone to two strong sides. High rise looks and is more period. Dropped holsters are easier to draw from, especially with longer barrel pistols, or longer arms. Reinforced is much easier to put the pistol back into. Drawing a pistol can be done from almost any holster, some better than others, but putting the pistol back in a collapsed holster presents a problem, some times taking two hands. Holsters that cover the trigger guard makes you draw the pistol by the grip, a cut down holster (this applies to two strong sides) allows you to pull the weak side by the backstrap and trigger guard, making the transition to the strong hand much faster. hope this answers some of your questions.