Hi Scuba Squared.
Fins.... Split fins are generally though to be faster in a straight swim (less fatiguing), but not as effective in sculling to hold a postion, or turning tight. Photographers, who hang around a lot, tend to prefer paddle fins. I've no particular place to go, and have a perfectly good pair of paddle fins I bought in 1997, so don't own splits.
The other important difference is between full foot and foot pocket fins. Full foot fins are worn with naked feet, and are favoured by a few people who dive from boats in warm tropical seas (like me), or who trave a lot and like to keep it light (also like me). Those who dive in cold water, or who shore dive in areas with rocky entries (like me occasionally), much prefer the foot pocket fins worn with booties, 'cause let me tell you, walking on those sharp rocks wearing a tank is for idiots (like me). I won't comment on cold water divers, because I might have to do that someday.
In choosing fins, if possible, go to a dive shop with a swimming pool and try out several while wearing your gear (don't do this without gear on as the characteristics of the fins will be quite different under a lighter load). Color is more or less immaterial, but flouresent colors are more visible at depth, a consideration if you are buddy diving. Men generally buy women pink gear, because they think they will like it, but ever since a certain Genesis ad five or so years ago, I personally have been partial to girls in yellow fins.
Hope thats useful.
Tim