Going back to the original question from Bernie, there appear to be two components. One is whether you need something other than a normal mouse to play and the other is the nature of the controls.
Most FPS games only require a normal mouse. although sometimes gameplay can be enhanced by using another type of controller. I use an optical cordless mouse for greater ease/sensitivity (and now miss it as I wrestle with thumbsticks on the Xbox 360!), but that only has the usual buttons.
As to the second part of the question, in my experience most FPS games rely on the mouse for aiming and shooting, but you will also need to use your left hand on the keyboard to move and perhaps perform one or two other actions. However, this is not usually complicated and often you can reconfigure keyboard controls to suit your own particular preferences.
I regard myself as pretty ham-fisted on the keyboard, but I still manage to play FPS games with enjoyment!
As to recommendations, it is always a matter of what appeals to your imagination. Some folks like military games (Call of Duty etc), others prefer space/monster shooters. I am very hard to please, and still find HalfLife 2 a very hard act to follow, best obtained in the Orange Box which has the additional joy of Portal. I also thoroughly enjoyed some of the earlier Prince of Persia games. There is more to them than mere gung-ho blood lust.
It is probably worth mentioning that weaponry usually starts simply (in HalfLife with a crowbar!), but that as the game progresses you are likely to gain other options: do not let that put you off as you can still stick to what you prefer and will usually be able to select an alternative weapon quickly and easily even in the heat of battle.
I hope that these comments are of some help.