A thickness planer is only good down to ABOUT 1/8" thickeness. Thinner than that and it tends to lift the wood and shatter it. Thickness of laminates is dependent upon the use: that is, face veneers for fiberglass laminated bows can be almost paper thin; additional lams for strength will be whatever is needed to develop the proper strength; lams for all wood bows tend to be thicker than those in glass laminated bows. Lams can be, but don't have to be tapered. Tapering allows for more flexibility in the tips of the bow; probably of more use in recurves than longbows, but not limited only to recurves. As for the lams that your neighbor cuts being wet, if they're thin they wont be wet long! Be sure to seal the ends to limit checking and sticker them as they dry just like you would any thicker piece. If you have a bow oven you could even dry them in it. I almost forgot to mention, if you want lams thinner than 1/8" you'll need to sand them to get them that thin. A thickness sander is best for this, but a drum sander can work if you work slowly enough to eliminate any scalloping.