No way would I risk pressing it without talking to a conservator first. Heat can easily discolor old fabrics permanently. S/he could not only answer your question about pressing, but could also advise you about what needs repair and the best way to do that. Are you trying to make it useable again, or just neaten it up for display? An appraiser might also be able to give you some advice. Conservators can be found through museums, historical societies, state quilting associations and places like that.