They did make 97+ nonpower mirrors. As far as I know 97+ mirrors were available in 3 levels: plain (nonpower, had to stick your hand out the window and move the glass), electric, and electric + heated. There may have also been a manual version with the little joystick on each door inside, but I haven't seen it. I just pulled a power+heated mirror, a power+heated mirror with a broken housing, and a power mirror with an OK housing and combined them into a pair of power+heated mirrors for 97+... going to be trying to retrofit them to my 96 with manual mirrors soon. I'm expecting it to involve a small amount of electrical fab work.
I think the mirrors themselves are bolt-in (right?), but the wiring for your pre-97 power mirrors may be different - actually, any chance you could post a picture of the connector for them? 97+ have a 6 pin red connector, same pinout for heated/non-heated except that the two wires for the heater are not present on the mirror pigtail itself for non heated mirrors. Swapping the glass for heated mirrors is fairly easy, once I figured it out, it took me approximately 15 minutes.
As for swapping to manual windows - looking in the parts catalog, it looks like the door shell itself is the same part number either way, so the differences should be entirely bolted on or at worst riveted on hardware. If you get yourself a 94-96 parts catalog you want to look at group DXJ - DOORS & RELATED PARTS CHEROKEE. I believe you may have to change out the window regulator and some rails as well as the trim panel but that should be about it; you can probably just clip off or drop the wiring harness if it isn't clipped to the inside of the door.