This is a common question. The question is not what a software does, but what you really need. Then you'll find the software by testing it for a long time (i'm not sure photoshop 30 days is enough)

IMO Photoshop doesn't really supports 16bit and CMYK just because when you switch to these modes, a huge amount of functionnalities are made unavailable. The workflow is working in RGB as long as possible then export.
RAW pictures can have higher bit-depth but you can use ufraw (gimp-plugin) or rawstudio (simple), digikam (use too) to manage this. IMO too, Photoshop doesn't really handles RAW, which is the job of Camera raw (in fact using the dcraw library like digikam and ufraw) or Lightroom in adobe's product.

If you just begin, try gimp and if it doesn't match, you can try photoshop later. Any knowledge you'd have get in Gimp will still true in photoshop. Personnaly i used to be a photshop teacher and i switch completely a long time ago, but you're not me.

Mainly Proprietray ecosystem try to phagocytate many applications ... Free ecosystem is working with more specialised tools (qtpfsgui, hugin, digikam) which complete the workflow).

pygmee