Good luck with the surgeries. As long as you have an experienced surgeon, you should be just fine.
Reports from Cleveland Clinic place pouch failure at around 5-10% over 20 or so years the operation has been done however, recently, they place it at around 2-5% and cite most failures from a change in DX to Crohns or occurrences Chronic Pouchitis.
Most people have 'good' results, in that they are able to deal with their 'new normal.' For me, adapting to the J-Pouch and getting used to this new normal has been easier than getting used to the bag.
No one will be able to tell you what your frequency is, but most have between 4-8 during the day and 0-2 at night.
Personally, I'm 4.5 months out and go about 6-7 times a day and can sleep at night for 6-7 hours without going. I'm sure things will get better as the years go on, but currently I couldn't be more thankful for my results.
I wish you nothing but the best, and I am sure you will be pleased with your results and start living life again doing all the things the bag restricts you from!