Hello, hamsterbait,
Sorry you have to deal with cancer. I have nothing as comprehensive to advise as cofty laid out. My cancer was not in the same class as colo-rectal. Mine was anal canal, a squamous cell cancer. The chemo drug was called 5FU (fluorouricil) which I fondly referred to as fu**you5.
On the use of pot: Nausea was a problem.They gave me drugs for it . A fine young fellow (xJW)kindly brought me some high quality pot that I preferred for the nausea, though I didn't often use it. My nurse practicioner inquired on my drug regimin warned that if I used pot and didn't know if it was pure,clean(as in the regulated medical marijuana) to not use it.
I drank a lot of water and took probiotic suppliments.I frankly had trouble eating--I usually have a hearty appetite. It wasn't until after my 6 weeks of radiation/chemo (no surgery) that my appetite came back.
Go for it, Ham. This may sound bizarre, but use the time to pull the loves of your life close, really close and revel in it. That is the good part.
Maeve