Hey, I haven't had exactly what you're talking about, but am in a similar spot except maybe a bit further down the road.
First of all, as to the reconstruction: I had my pouch re-sized in 2009 and it was a fairly rough surgery in that it took a good 6 weeks to gain back strength and so on, but was "normal" and progressed well. I don't know how this might relate to having the j-pouch completely re-done, but just to say that having one's pouch "messed with" isn't necessarily too terrible.
Now, present day: I am post-op from a pouch advancement specifically done for a fistula. I tried other repairs and so forth for 3 years, tried living with it and so on, but the blasted thing kept growing and getting worse. Toward the end (the past 6 months or so) I was on a constant merry-go-round of pain, yeast infections, and UTIs. The thing was so big by the end it could be seen with the naked eye, yee haw.
Mine was located just barely above my rectal cuff, so that is why the pouch advancement was recommended. (My other option was a muscle graft, but two experienced surgical departments at two different hospitals agreed that the advancement was the better option.)
It was two-step procedure: on June 26 the fistula was literally cut out, the surrounding area stitched back together, and then the pouch was rid of scar tissue and so forth, cut loose, and moved down; I actually had a bit of tissue hanging out of my anus. After two weeks, on July 10, this tissue was trimmed and stitched into place. So I am now just about three weeks post-op from that second op (which was quite short).
So a bit of a different procedure than you're having, but some similarities.
The worst part for me has been the incontinence. I am just now beginning to gain some control. Sitting can be quite painful with all the stitches down there, so I recommend a donut pillow!
And no, the hospital stay does not sound excessive. It all depends on how long your gut takes to "wake up". Are you going to have a temp stoma? Normally here they do that for this procedure; I was also supposed to have one but my small intestine was too scarred up so they didn't want to risk it. Of course, the incontinence issue is much less with a stoma!
Anyway, hang in there and all the best. If you have any questions that I might be able to answer, ask away.
Gin