Changed a rear wheel bearing on one of these. Good strong set up but a pain to do.

Scale of 1-10, how hard?

I was fortunate to have access to a good, industrial hydraulic press. Removing the axle from the vehicle wasn't hard. Setting up the axle in the press so we didn't bend or mangle the backing plate was the hard part.

I see, good to know, thank you!

Previa's are pretty easy to work on for a mid engine car. Parts availability can be problematic though.

so I've noticed...

Is it RWD?

it is, indeed

That helps a lot. What all is wrong with it?

Mostly cosmetic things (save for some proper rust where the windshield meets the roof), however, mechanically: it's got a squeaky belt (not sure which one specifically, but I have some guesses) on startup and when turning the wheel, but it stops squeaking after 30 seconds. I think I have to replace a motor mount due to a loud rumbling when idling, not entirely sure though. Last thing is this rumbling noise between 45-55mph. At first I thought it was a wheel stud, then a loose wheel, then a wheel bearing, but the people I took it to when I got it said they changed the bearings, and everything about the wheel assembly looks good, so only god knows what that is.

A shaking while moving at speed while on throttle is often a driveshaft or an axel. But it can also be motor mounts.

This is good information, thank you!