Hi there arick,
You will need to attach the drive with SATA to USB adapter, externally, to another computer.
In case the drive is recognized over there, or at least by Disk Management, you can run some data recovery tool on it. You may be able to retrieve at least some of the data.
If the drive is nowhere to be recognized, then I believe you will need to contact a data recovery company, in case the data is really important.
As for the new drive, yeah, RPM do matter. With a faster drive (7200 RPM instead of 5400 RPM let's say), you will get faster boot and loading times. You can even consider getting an SSD, which would significantly improve those.
As a WD representative, I can't really comment on any other brands.
If you wan to...