1) In most of GPU are VGA port so i think there won't be any problem. But i still recomend you buy new monitor for god's sake you will save your eyes and some energy
2-3) about GPU read in internet you will find lot of information there
4) if you are not very sure find other part i can't tell you everything
Your new graphic card choice is neither here nor there with your old monitor, both will manage fine, but again, get a more recent monitor with higher resolution, your eyes will love it.
Usb 3.0, you can get frontplates for Usb 3.0 that will plug into your mobo but unless you have any usb 3.0 devices its pointless as they will run at 2.0 speed on a 2.0 device,
I hope this helps but ask anyything else you need to
Theres also a step by step building/troubleshooting guide up the top of the section,
Sections three and four will be of most use http://www.tomshardware.co.uk/forum/288241-13-read-post...
Ok, I'll get a new monitor after a month or so of the build. I still don't get the USB 3.0 part. Is it a big needed thing? Or will it be just a thing I'll never use? Honestly I don't know what it is or what's used for.
Its just usb2 but faster, in time there will be more usb 3.0 devices like external hard drives and you will see a benefit, but for now its not a worry point, if you plug anything usb2.0 into the usb3.0 socket, it will just run at 2.0 like normal
you can buy a front panel like I said, and you will have usb 3.0 sockets on your case but they will only run at usb2.0 speed, unless the device itself is usb3.0