For #1, there are several options depending on what exactly you want and how you want it displayed.
If you just want to see your own DPS, this addon will display it for you in any LDB display you may already have installed:
http://www.wowinterface.com/download...Block_DPS.html
If you would like a barebones display, minimal on the features, but still able to compare your dps to others', this is what I use:
http://www.wowinterface.com/download...0-TinyDPS.html
For #2, again, there are several options that will display your inventory in one window with sorting.
tBags seems to be updated here if you haven't tried it:
http://www.wowinterface.com/download...urrencies.html
In addition to AdiBags, linked by myrroddin, there is ArkInventory, Combuctor, bdBags and DJBags.
For #3, I can't think of anything at the moment that can do that for you. I don't think Pawn has a way to do a whole "outfit". You could try
http://www.askmrrobot.com/ but I don't remember if it can pull what's in your bags from the Armory. But you might be able to tell it what you have. Oh, I do see a "best in bags" button.