1. Mandrake *should* recognize your SATA drives. If it doesn't, or you have other problems, I would suggest posting specific questions in the Mandrake Distro forum here, or at the Mandrake Users Board
2. The standard download edition of Mandrake will work just fine in a 64-bit machine. The AMD64 chip natively supports 32-bit apps (and OSes).
Mandrake *does* have a 64-bit version, but IIRC, it is currently a "pay for" item.