The faux pearl bead trims won't wash or dry clean well, so they have to come off no matter how you clean the dress. Your late 1930s wedding dress is velvet, I would not wash it, otherwise you will have a clean, crushed velvet dress that you will never be able to get the crush marks out of. Dry cleaning is your only option and stain removal by dry cleaners is very iffy. They will be able to freshen it up, deodorize, and maybe get some overall dusty dirt out, but chances of them removing any stains are slim. First thing I would do if I were you, is vacuum it thoroughly, using a brush attachment (don't vacuum the beadwork or you might lose the beads). You could then steam it from the inside, and see what you think of it then before making any further decisions about cleaning it.