for the case, my main question is whether or not 1 rear fan is enough. i have seen a fair number of posts where people have 3+ fans in their case. will my stuff be ok with the 1 stock fan, or will i have to add additional fans?
Whether one fan is enough will depend on a few factors but in your case with that video card I'd say no.
IF your computer was for web browsing, email... etc using on board video, or something like a 7300 then yes you'd probably be ok with just one fan. Also, depending on how many hdd's you put in the rack (which is where your intake is) you may block the air flow, a fan in front would help push cool air in past your hdds.
Even if you discount the 4 fans on my radiator (for my water cooling) I still have 4 other fans on my computer. If you are worried about the noise then either get a fan controller or fans that are heat controlled.
If you have one hdd then you can fit it into the space for the floppy if you aren't using one. The hdd cage sits directly behind the optional front fan placement. I also didn't mean he needed the fan there to cool the hdd's, I meant that the cool air would be forced past the blocking hdd's into the rest of the case.