Re: drive letters
If you want to guarantee that all system and boot files go on the C drive, you should ensure that the only formatted partition or disk available to Windows at install time is the C drive. Do not create any other partitions at install time.
Best to disconnect any other disks or remove them using the BIOS before installation.
You can create further partitions and add disks (and adjust the drive letters) to your heart's content after that.
SD