Voirin, here is the answers to all your questions but remember: it is only good advice if you take it.
0. Personally, I do not think this is a good board to buy. I got it with a bundle for dirt cheap which is the only reason why I have it. It uses a VIA chipset which in general gives lower performance and a LOT more headache. As far as being able to attach 6xIDE & 4XSATA, I believe the MSI K8N Neo Platinum allows the same amount and is based on the MUCH better nForce3 chipset.
1. Socket 939 is true option. You WILL spend more on a 939 board and a 939 processor, but in my opinion if you are buying new hardware you want to be as close to on top of technology as you can within reason & budget. You can get a good 939 board (MSI makes an excellent one as well with the nForce3 chipset) and 939 processor for not too hefty of a price. For instance, MSI K8N Neo Platinum for ~$130USD and Athlon 64 3200+ (1MB L2 Cache) for ~$214. On the socket 939 side, MSI K8N Neo2 Platinum for ~$180 and Athlon 64 3500+ for ~$350. If you have it in the budget, go socket 939. You are closer to the current level of technology and therefore will be able to upgrade for a longer period of time. You also are able to use dual-channel RAM on the socket 939 boards in addition to other performance enhancing features.
2. Pretty much all boards will come rated at DDR400, because that is the only "standard" accepted for use on them. However, given the high "FSB" speed of the A64's and the tendency of people to OC them, high speed memory is a must. ADATA PC-4000 will work, but depending on how you want to overclock, you cannot beat Corsair, OCZ, or Crucial for some high-speed, high OC'ing memory. As always, you will pay more but you DO get what you pay for.
3. The K8V is HORRIBLE at overclocking. If you buy this board, don't even bother. That said, the other MSI boards mentioned are superb OCers. If you ARE looking at overclocking your system, remember that for it to truly be successful and worthwhile, you must use high quality components in everything. This means CPU, mobo, MEM, and most overlooked POWER SUPPLY. Cheap power supplies mean little to no OCing and more system instability in the first place. Personally I recommend Antec, Vantec, or OCZ for PSU's.
4. As far as the latest revision goes, dunno. Order and hope. If its not the latest, RMA it and see then. You might call whoever you are puchasing the board from and see if they have that info available, but generally you cannot ascertain that from a website.
I hope this answers your questions and I also hope you choose not to buy this board. Sure, its okay for a basic system. But given the number of problems you are bound to have right out of the box, the lack of OCing ability, and general crappiness of VIA chipsets, I really hope you go for any kind of nForce3 chipset. Check out AT's latest motherboard reviews and you will see how the MSI nForce3 boards lead the charts. Good luck and let us know if you have any questions
NOTE: Even though I got this board for practically free with a sweet EPP bundle, I plan on purchasing the MSI at some point in the near future if that tells you anything about this crap board.