Can many months of cdif & tx make your colon more likely to perforate from colonoscopy or sigmoidoscopy after its cured (test ok & no sx)?

No: I am not aware of any data to suggest this.

Depends : An inflamed colon is at higher risk of complications during colonoscopy as it tends to be thicker, more blood flow, and less flexible. If your colon has recovered from for C difficle colitis then your risk is back to normal. If you have been chronically ill and you are malnourished as a result you will have a slightly increased risk as well as a decreased ability to recover from a complication.