Nah man! Long posts are cool with me. I wish my dumbass computer could handle TF2. I haven't tried it in a while actually. I may try it later today.
I never really enjoyed single players / co-op games. I may look up some borderlands 2 gameplay and may end up buying it...
As for the CoD thing, it's a bit more complicated then what you're thinking.
Each gun has a higher or lower rate of fire, accuracy, damage, mobility, and range.
There are normally around 5 or 6 classes or primary guns. Sub Machine Guns, Assault Rifles, Sniper Rifles, Shotguns, Light Machine Guns, and Special Weapons.
SMG's are mainly for small maps. Good for running fast, and spraying.
Assault Rifles are better for larger, more open maps where you have long hallways or long ranges of vision where you may get stuck with an SMG.
Snipers (In my case) are for any situation in which I feel like making people feel bad about their skills (If I wanted to sound cocky ;) and by that, I mean quickscoping. Alot of people have different opinions on quickscoping. Some people say it ruins the game. Most (Logical) people say that it takes much more skill than using an assault rifle, SMG, LMG, etc. The other way to use a sniper is the obvious one. Camp back in an area where you have a large field of vision, and usually looking towards a place that is a "High traffic" area.
Shotguns are what you'd expect them to be. They are a one shot kill (Depending on how close you are to the person and which shotgun you choose), they come in my types (Semi-Auto, Full auto, and Pump action), and are mainly used on small maps where you might find SMG's being used.
I don't use LMG's much, but some people like them. They are mainly used on large, very open maps where you need to fire lots of bullets because you'll be seeing lots of people. They have a large clip capacity and carry a lot of ammo. Good for things like Domination, in which you need to capture flags to gain points to win.
And finally, Special Weapons. They aren't in every game, but in Bo2, the only primary special weapon is the Assault Shield. The assault shield is usually used to goof off ingame and mess with people. In this game, you can deploy your assault shield and stand being it and let it take bullets while you fire at people from behind it.
If you actually read all of that, you're awesome.