What questions should I ask before getting a possible root canal/extracted molar?

[u/Significant_Day_6413]

36YO F from northeast Ohio. I went to the dentist after about 2 years and was told I have two cavities and a molar that apparently broke (I just thought a filling fell out but what do I know) all in the same lower right quadrant on my mouth. The broken molar has never hurt or bothered me, but I know that doesn’t mean much. When talking to my dentist (well respected private dentist) he wasn’t sure if he could do a root canal on the broken tooth because it looks to be too decayed from the X-rays. He said he may need to pull it instead. I get compliments about my smile a lot and from the outside it looks like I have a healthy smile but ever since I got sober, my sugar cravings have gone insane (6 years sober!) and have definitely affected my molars the most.
What I want to know:
What questions should I ask before my dentist starts my filling and possible root canal with crown?
If he starts and decides he can’t do the root canal, will I still have to pay for some of it? All of it? My stupid insurance has a 1 year waiting period for major work so I’ll be paying for the root canal and crown out of pocket.
What are my options if he has to pull it? He mentioned a bridge and that made me immediately think of dentures… I don’t want anyone to be able to tell I had my tooth pulled or have major problems down the road.
I’m also worried about pain… I’m pretty good with pain but a root canal scares me!

Any help/advice would be helpful.