Lelly... ask about whatever is on your mind. When I was in the whirlwind of diagnosis, surgery prep, etc., I didn't even know what to ask because I didn't know who to ask.
As far as experience with these rare tumors, there isn't a lot out there just because they don't happen very often. I went to Vanderbilt University in Nashville for my surgery. They are a highly rated facility for bladder cancer. I got referred there because my local uro said he didn't know anything about treating me because he might see one case like this in ten years. Even though Vanderbilt was 300 miles away, it was the right decision for me.
At my first consult with my surgeon, I asked about chemo and he said he wouldn't even know what type to use because there really wasn't a protocol for it. Keep in mind that he already had the path report from my initial TURB when the tumor was removed by my hometown uro. My tumor was in the perfect place to allow the partial cystectomy procedure. Unfortunately, not all adenocarcinomas meet that criteria.
I don't have a guess as to why your doctors are looking so closely elsewhere, but hopefully they are just being thorough and careful. You could just ask them why and what they are looking for. Maybe it's just because it is rare for adenocarcinomas to start in the bladder (aka primary) since it is the same type of tumor that is often found in cases of colon cancer, but they ruled that out already for you.
If you, and your doctors, are certain that bladder removal is what is needed, then another TURB is most likely not needed. That is generally done to check the results of the first one and to confirm the diagnosis. At this point after all the tests you've had, a diagnosis should have been firmly determined.
I'm so sorry you're facing this challenge. I know you are tough. You've faced 90 miles of bears and whitewater rapids. You know how that fear felt. The fear of bc is paralyzing in the beginning when all these decisions need to be made. There are many here who live very normal lives (although it is a "new" normal) after cystectomy, and you will too. We will be here to help you get through it by answering any questions you have along the way.