If this is a retail Vista installation DVD, then you can use the Premium disc to install Basic with your product key number. You can only install the edition of Vista that the product key number is for. You will not be able to install Premium with the poduct key number for Basic.
Yes, you will be able to use the product key on the other disk. However, since it is a BASIC key, you will only be able to use it for that version (either 32-bit or 64-bit). This is similar to what I did when setting up my system to multi-boot. I had an original Home Premium disk (without SP1), but I then subsequently got the Ultimate version (with SP1, both 32-bit and 64-bit). I used the Ultimate key with the 64-bit disk and the Home Premium key with the 32-bit disk, although I could only install the Home Premium version with it (obviously). This is because all disks contain all versions of Vista, and it is the product key used which determines which version is installed.
4 x 4GB DDR3-1600 Corsair Vengeance CMZ8GX3M2A1600C9B (16GB)
Graphics card(s)
MSI GeForce GTX770 Gaming OC 2GB
Sound Card
Realtek High Definition on board solution (ALC 898)
Monitor(s) Displays
ViewSonic VA1912w Widescreen
Screen Resolution
1440x900
Hard Drives
OCZ Agility 3 120GB SATA III x2 (RAID 0)
Samsung HD501LJ 500GB SATA II x2
Hitachi HDS721010CLA332 1TB SATA II
Iomega 1.5TB Ext USB 2.0
WD 2.0TB Ext USB 3.0