Bunny hopping? As in constanly jumping through the level? Whats wrong with that? Just pull out your gun and kill the jumping player.
Bunnyhopping is not simply jumping, but a engine-exploit which allows you to move much faster and evade enemy fire much easier.
It doesn't work in most engines nowadays, because jumping has become much "heavier" (in motion). But I think Counterstrike gave a pretty good idea of it.
Ive read people complain about players dive to the ground and shoot people (COD:BO), But they are still just as easy to kill as some1 standing or crouching.
But Dolphin diving I am unfamiliar with. Dropping onto an enemy from above? or jumping off an edge to avoid enemies?
I think the first thing you're referring to is a "dropshot", which basicly means to instantly go prone when fighting someone, thus minimising yourself as target and maximising your accuracy at the same time. A good reason not to have "prone" in the game.
Dolphin diving is basicly the combination of bunnyhopping and dropshotting.
Lights can apparently double jump now to get over those high walls.
I think they can do walljumps, but no actual double jumps like the Scout in TF2, for example.