Hello,
It sounds like you have a power supply problem causing the unxplained crashes.
The 'insert volume DF0:' is because in your S:Startup-sequence is the line, Addbuffers DF0: 15, which will cause AmigaDOS to look for the floppydrive. You can comment this out.
I am unsure why you are getting HDD errors, they could be power related or cabling related.
Have you triec cleaning the lens of the CD32 with Isopropyl alcohol on a cotton bud?
The laser units can be re-aligned (I wrote the guide on this) but it is not an easy task.
Is the noise on accessing the CD drive coming through your speakers or heard from the unit itself?
HTH
Ian