I agree 100% to Yuki, a damn fine thread.
One thing that you can add to the shotgun part.
When using a pump action shotgun it's not as easy as you think to just "Pump" it. I've seen my friend's brother try to rooster a shotgun and it was hilarious how he tried. After about 5 minutes of laughing I ended up taking it from him, and hitting the release button just below the trigger which releases the lever to allow roostering of the next shot. It takes some skill to fire a pump shotgun in rapid succession.
Another thing which in 98% of all shooting games is the ammo count and loading system. In all games I've seen except 1 is when you shoot a burst of rounds, hide around the corner for a quick reload. Example: You have an M16 and you're playing Call of Duty, You have 30 rounds in your magazine, you do a quick burst and now you have 19 rounds in your magazine, which means you have one round already inside the chamber waiting to be fired, that makes 20 rounds all together out of the 30 you originally had. Now you reload, you take the magazine out with 19 rounds inside, and throw in a fresh magazine. We'll stop right there now. In real life if you do this with a fresh magazine of 30 rounds, and let's back step here, remember when I said you already have one round in the chamber waiting to be fired, you then insert the new magazine with 30 rounds in there and in REAL LIFE you would have 31 rounds, commonly said in the gun community as when you see a gun they normally say "Oh this gun loaded holds 8 plus 1" The plus one means one already loaded in the chamber.. In pretty much all games, don't quote me on this because I know of one game that follows this rule, that when you reload with one already in the chamber in most games it doesn't feature this rule. Instead you have 30 rounds now. Where did that one round go? The game that I'm talking about that does follow this rule is Tom Clancy's Rainbow Six: Vegas 2. I'm not sure if any of the other Tom Clancy titles follow this but I'm using that as an example.
(Apologize for any mislead statements, I haven't gone to sleep and I've been up since 6pm yesterday.)