i think php could do this of course its really up to you as every person has their own favorite language to code in
lets just put it this way:
if your running on a linux server php,mysql, perl,,c++ is your way to go
if your running windows, asp,asp.net access is what you want
some other server it might not really matter
i just said that above statement as if your on linux php and mysql will run best as its created for linux it will work on php but not as good and the same goes for asp on linux
so its whaever you like to code in and what you like the most
2)that depends on how well you think your coding skills are

if you dont have any that either try to learn one or see what language the web dev wants to use
3)depends on how much goes on there and what files, its hard to say but i will tell you its a big number my friend maybe 10 or 20 gigs give or take.
your adding the traffic, the downloads and downlaods will suck ALOT of bandwidth depending on how big it is
