1. For general purpose a knife you have is better than a knife in a drawer. So a light folder is what I carry 99% of the time. Sebenza, Spyderco, Benchmade, Kershaw...doesn't matter much.
2. Spyderco PM II
3. Large fixed blades aren't as good for skinning as a 3.5" blade. You can use a longer blade, but then you don't have the fine control. Scalpels aren't generally 12" long (and yes I know there are long handled scalpels).
4. Those Wolverine claw knives and Nightmare on Elm Street Freddy fingers seem pretty gimmicky to me.
5. A good fighting knife? Ka-Bar, Sykes-Fairbain, various bayonets. Busse Team Gemini cannot be beat for zombies.
As far as steels go, the heat treat is very important. I sharpen a bunch of kitchen knives for folks from church. Most of the blades are horribly soft. They will form a burr after just a couple passes on a 250 grit diamond stone. This makes them easy to sharpen, but they dull very quickly. Some Japanese knives (my set of Shuns) are so hard that they chip if you look at them sideways.
For knives that rust, I like 1095, 1084, 52100, 3V, O-1, A-2, Infi, Hitachi white and blue steel, Sandvik (or whatever is in a Mora), CPM M-4...depending on the heat treat.
For stainless S35VN, 154CM, M390, S90V, Elmax, etc.
Stick with reputable companies or makers with good guarantees, handle the knife before you buy if you can, and then go buy a Murray Carter Neck Knife. Or a Fallkniven F-1. Or a Mora. Or a Winkler. Or a Busse. Or a Carothers.