FelixGust, I am 7 years out from my J-pouch surgery and I still have good days and bad days. I seem to have avoided chronic pouchitis, but I have learned to live with feeling like I need to use the toilet more than I actually allow myself to go. (Most of the time, it is gas--that seems to be the real enemy to a J-pouch, aside from pouchitis). I really don't count how often I go, but it is probably 6-9 times a day, including the middle of the night or early morning. I use Calmoseptine after each bowel movement to protect my anus. That seems to help a lot. With time, you will figure out what works best for you.
As for the straining, keep in mind that with no solid stool coming through your anus, your anus will shrink. I have found that this creates some straining when I go. I have recently experimented with stretching my anus out by using a device that is used for vaginal stretching (but it needs to be super narrow!!!). I haven't been doing it reliably enough to know if it is effective.
Good luck with everything and stay on here---the people here will help you through!