Welcome ckfun,
Sorry for your reason to be here. Yes, the diagnosis is serious but, there are many with worse situations and still standing. Stage T3 is better than T4. Also, I have learned it is always one day at a time. That is all one can control.
Adenocarcinoma is not your usual "garden variety" of bladder cancer. The best advice I can probably give is make sure the surgeon does many of these a year (25-35+) and if you have any doubts sometimes a second opinion is good for confirmation and fresh eyes. However, being stage 3 you do want to act quickly. It sounds like your Doc has a good plan and yes that kind of radical surgery gives the best odds of survival which to me means almost nothing as everyone responds differently and attitude with you as a caregiver are good things. Pat yourself on the back. This is still beatable and treatable!
I am leaving with a good site for the different diversions with pros and cons (just copy and paste):
my.clevelandclinic.org/health/treatments/12546-urinary-reconstruction--diversion .
Ask away as you have other questions.