Unless you want the Lexicon Pantheon or Cakewalk Tuner last bundled with 8.5 or Cakewalk Analyst or Beatscape last bundled with X1.
WRT, the drive choice, the easiest would be to install everything on the SSD and use another internal drive for projects. When/if the disk starts to fill up move the samples to another drive and create a directory junction in the original location. For example, to relocate the DimPro multisample folder from "C:\Program Files\Cakewalk\Dimension Pro\Multisamples" to "D:\Cakewalk\DimPro\Multisamples"
1) Using Windows Explorer move "C:\Program Files\Cakewalk\Dimension Pro\Multisamples" to "D:\Cakewalk\DimPro\Multisamples"
2) Run the cmd.exe as administrator and type
mklink /j "C:\Program Files\Cakewalk\Dimension Pro\Multisamples" "D:\Cakewalk\DimPro\Multisamples"