The problem with plywood is getting in from here to there. It's heavy and getting a good grip is difficult...especially if you have to carry it for any length of time. An easy solution is to take a couple of C-clamps and tighten them on to each end. This will give you the handle you need to get a good, solid grip.
Lead-based paint is usually not a hazard if it is in good consition, and it is not an impact or friction surface, like a window. It is defined by the federal government as paint with lead levels greater that or equal to 1.0 milligram per square centimeter, or more than .5% by weight.