Actually I did not properly read your third question, but it is in fact still true... the drive is 3TB and I only have a couple hundred gig on it so the free space is around 2.6TB
This is a known issue with the installer that other people have reported in these forums -
Re: Can't run Oracle 11g r2 setup.exe on win2008 r2 sp1 x64
Can you use a smaller hard drive (< 2 TB) or partition the one that you have ?
I am assuming this issue will be fixed in a future release