A great effort and well thought out, and I'd certainly agree with Larry's additions. But, and there's always at least one. Getting any lathe including brand new to actually cut truly parallel takes a fair amount of time and effort. At least that's so for anything that fit's a bench top lathe description. Even set as exactly as possible with the best level you can afford that pre set level condition still isn't a finished job. Very fine tweaking by very slightly counter twisting the lathe bed just barely outside that dead level condition is still required to help off set the usual machine deflections caused by the cutting forces. Almost always that's done at the tail stock end. My largest lathe sits on a pair of heavy 1" thick steel plates with screw adjustments at each end of the bed so those fine tweaks aren't hard to do. Maybe the multi ton industrial level lathes don't need that fine adjusting beyond being level, but I've proved by measurements the lighter one's always do.
Well finished and sealed wood does slow the effect down, but one way or another the unstoppable characteristic's with any wood are that it's going to move and more than enough to matter to those fine settings. My lathes are bolted down to those steel benches, unfortunately due to personal reasons and finances my home shop has the usual stick built wooden construction as it's floor. The lathe, benches there on and everything stored within it are at least 1200-1500 lbs. That bench material, added weight and even the lathes built in rigidity doesn't matter or make any difference at all. I can leave a precision machinist level anywhere on the lathe bed for a few hrs and see more than measurable differences over even those few hrs as temperature's and more importantly humidity levels change through out the day. Differences between day - night, summer - winter create far larger changes. The floor itself is moving and it's impossible to control. Your bench will do the same. Wood IS going to move and it's not a consistent amount through out even the same piece of wood. Your expected accuracy levels may well be within what any of those changes might be or not for that new bench. But to get the very best out of any bench lathe then a concrete floor and at least a steel bench isn't optional. I can and have adjusted my lathes so at least one of them is capable of very low 10ths differences in a shafts diameter that can be measured over a 12" length. At best those adjustments will only hold for a very few hrs if I'm really lucky. Fwiw if you end up seeing those same changes there's one thing that can sometimes help. Only bolt the head stock end of the bed down to the bench and allow the tail stock end to semi float on the bench top. The wood in your bench will still move, but most times doing it that way does help to slightly lessen the effect. It was and is a design element on quite a few older light weight bench lathes and even more so with the watch maker types where the whole lathe bed has only a single mounting foot and the rest of the bed is cantilevered out into thin air. They were designed that way since it would be expected most lathes of that size would most likely be bolted down onto some type of wooden bench. Wood also has by far the biggest change due to humidity across it's grain structure or what's generally across the width of a boards face, a far lesser amount through a boards thickness, and the least movement change over it's length. Most agree that for those reasons then quarter sawn wood is then the most stable. And slow growth hard wood will have a much less open grain structure over any of today's fast grown construction grade lumber. It's that open cell structure that allows the most and largest changes due to the changes in humidity levels.