So here's some info on bonus items offered by various deals. Armor in ME2 is broken down into catergories: head, chest, shoulders, arms, legs. The preorder armors are a full set though, and you ether equip the whole thing, or nothing. I got the Gamestop preorder armor/weapon, and the Blood Dragon armor from owning Dragon Age. Both are available from very early in the game (within 10-15 minutes probably), so here's how they compare to the default stuff.
Starting armor
Head: +5% health
Chest: +3% power damage
Shoulders: +3% weapon damage
Arms: +3% health
Legs: +3% shield strength
Blood Dragon Armor
+15% power damage
+10% shield strength
Terminus Armor
+10% storm speed (sprint)
+15% shield
+10% weapon's reserve ammo (yes weapons have ammo in ME2)
I was using the Terminus Armor on my soldier, but I think I'm gonna move over to the default stuff plus a new chest and helm I picked up. Storm speed doesn't seem all that important, as a soldier I can improve it with skill points. Ammo also seems to be in decent supply so the ammo reserve doesn't seem all that amazing. The Blackstorm gun from the gamestop preorder is a fucking beast though. It replaces your heavy weapon (right now I just have a grenade launcher), which starts with an ammo supply of 2 (any heavy eapon you pick up has that same supply cap). It takes a second or two to fire a shot off, and then it sends a black orb toward the enemy and sucks in anything within a few meters, and kills them all in one shot (assuming they're not tougher enemies, I think maybe biotic resistances might factor in). It's great for clearing out crowds, but then so is the grenade launcher. Of course the grenade launcher could do some work on a really tough enemy, but the Blackstorm would probably just fizzle.
A few things to clarify:
-Armor has no stats, just bonuses like what I listed above
-Weapons aren't looted, you just buy them or find them at specific places and then go back to a weapon locker to change your loadout. They're more permanent though. There's no "I found this amazing shotgun". Instead it's "the shotgun in ME2 is amazing". You can get upgrades, but it applies to any shotgun you use, and only works for Sheperd. I found a heavy pistol at a shop, bought it, and now I can equip it to every squad member simultaneously.
-You don't equip armor for your squad mates, just for Sheperd. You can change their weapon loadouts though (so far it seems like you'll just go in and switch everyone to "better pistol" whenever you get a new gun, and not do much else there)
-I bought some alien porn but don't know where to access it.