Having done apartment Woodworking years ago, IMO, you'd be better off finding someone who can resaw/ plane that slab for you, then you can jump in with all the less-heavy work to build your guitar. Plus, with a good resaw job you could end up with two bodies, or at least a body and a cap for another build. The high-quality, new ( if your budget allows) router is still a good idea. I hope you'll save the paint for another, more plain wood; it would have to be an exceptionally ugly piece of walnut to deserve being painted over. For me, once you start approaching final sanding on a piece of walnut, it is just magical how the natural grain, figures and color patterns emerge, worthy of enhancement and protection with oil or clear finish. Also, in an apartment, oil finish application is so much more do-able.