1. Updating VGA bioses is generally either for fixes from the mfg which seems fairly rare, or modified (see my GTX260 support thread's op for more info).
2. Either submitted here on TPU's Bios archive, MVKTech.com's bios archive or from the MFG directly. Check the mfg site to see if there was a bug/glitch/issue with the shipped bios, if not, odds are there isn't an updated one for that card necessarily.
3. There's a risk of "bricking" the card, or making it all but useless. You can sometimes "blind flash" an original bios back and revive the card back to working order, check the NV and ATI sections for "I messed up my vid card after bios flash" or "bios flash killed my vid card", I've seen so many of these threads even recently it's almost saddening. Be prepared, write down the correct commands, if there are issues with an attempted flash that won't go, don't keep trying. It helps to have a backup PCI/PCI-e card handy and to know commands for flashing your bricked card while using a different card. In my case with my old x1950pro, I had a garbled screen, I had written down the commands and filenames on a sheet of paper, so I just typed in the command for flashing the stock bios back, and saved it, card still works to this day.
4. Look up NiBitor, read my GTX 260/280 help thread, see near the bottom of the OP for programs and links to get you going. Google too, that helped me a lot in this topic for sure, I was hesitant till I read quite a few were bios modding their 260's w/o issues. Research and make sure you keep a backup of the original bios, just in case (one of the biggest errors, see many "I need this card's original bios asap!" threads? Many cases they didn't do this, or name it to something they could remember or write it down on a piece of paper, a number of preventatives make bios flashing a breeze, and it is after the first time, cakework. Just take the steps to doing it correctly and safely and you should be just fine.