Of course one of the first things you should do is run film through it - set up a test scene with constant lighting (vs. outdoors unless it's clear or solid cloudy - you want unchanging lights, so indoors with a bright studio light is best). Get a solid grey background (for B&W just a solid mid-tone of any color) and add something like a product packaging box with fine text. Or take a sheet of cardboard and a sharpie and make a big grid to check focus all across the plane. Stick a small whiteboard or card in there and mark shutter speeds as you shoot. Take it outside and shoot down your street, look for something distant to check infinity focus on, with all lenses. Run the film and grab your loupe - check for light leaks, accurate shutter speeds, etc. Check for fine focus (on the text). Check the film advance (overlapping frames or wildly different spacing between frames).
You might dedicate a roll to getting every shutter speed with the proper aperture to have the 'same' exposure - that way you can see if any speeds are wildly off. (IE f8 @ 1/125, f11 @ 1/60th, etc). There are testing devices for shutters but if you don't have one this will give you a good overview of where the shutter's at.
You can quickly blow through 3 rolls of 120 doing this, but if you process yourself you're looking at under $30 for a no-surprises test - well worth it, and it's the first step to getting "second nature" with a new camera.
Take a look at the foam seals, and google a bit or contact John Goodman and see if he offers a kit and if re-foaming is easy. Look for any place that would have foam for damping, too (maybe not an issue with an RF camera - SLRs often have foam to damp the mirrors, etc)