Wal, I've worked on 2 etching presses for my wife, and I think you are overthinking this. One is a small tabletop one, the other a beast weighing the best part of half a ton that sits on a stand on the floor.

Neither has anything very fancy in the way of bearings, just a u-shaped recess in a lump of steel or iron that a spigot on the end of the roller sits in. On the tabletop press I made a nice pair of CI blocks bored out to fit the spigots that slide on the edges of the slots in the sides, mainly so I could lift the roller using some springs to make it easier to manage, but the previous ones were just brass blocks with the u-shaped cutouts.

There needs to be a steel platen between the rollers that gets wound across supporting the plate and paper. On the smaller press this is 1/8 inch bit of mild steel plate, on the big one its 3/4 inch by 18 inches by 3 ft or so, a real brute.

You absolutely don't need any fancy thread on the pressure screws, an ordinary coarse metric thread would be fine. It doesn't get much use, the pressure isn't very great. Remember that there will be a felt blanket between the rollers and the paper that regulates the pressure and takes up any unevenness.

I'll try to take some photos for you and post them here, any questions just ask.