I am refurbing a 100 year old house. I am concerned about the presence of lead and asbestos (are there others?). More from a resale value standpoint. Probably the only way to tell what is on, or in those plastered walls and popcorn coated ceilings is testing. (who does, how much $ ?) If it is positive for them what options does one have with each? Can you just paint over them?