KK I have had zero side effects from Remicade. Some people claim that the infusion the first time they get it leaves them feeling "wiped out" (fatigued) that day, some say they are tired the day they get it. These people may be getting it with Benadryl. Anyway, it's never fatigued me, I never developed antibodies and been taking it for 5 years.
Imuran has been around since at least 1991. I was given Imuran as a last ditch treatment for UC and when it failed and I had to be taken off of it, surgery was inevitable and I had my colectomy in 1992. A lot of people have the liver chemistry side effects with Imuran. I should tell you as well that when I started Remicade, I took it with Methotrexate for around 3 years, but when liver chemistries rose they pulled me off the Methotrexate and they went right back to normal. Methotrexate is given with Remicade to suppress renal secretions of Remicade and to assist in preventing antibodies. But I guess since I had not developed antibodies in 3 years they felt It could be removed. You may need to start with Methotrexate around 12.5 mg and monitor the liver chemistries with blood labs every few months. In fact they will not infuse you unless they have blood labs less than 3 months old.
As far as your other questions I feel great, I gained weight and am out of shape due to Covid but so have many people. Remicade has the pouchitis under control at around 90%. There is some persistent inflammation at J pouch inlet and neoterminal ileum due to backsplash stool. But no symptoms - they were completely eliminated by Remicade.
After being on Remicade 6 months or so you should have a Remicade test to determine therapeutic blood level of Remicade. The manufacturer will send your Doctor a kit on that but ask about it.
Good luck!!