This is very common in the 60s and 70s tract homes in CA. I'm pretty positive the ceiling in our house in San Jose had it. We actually decided NOT to test it because we didn't want to know so we didn't have to disclose it at sale.
For the flooring, can you just re-tile right on top of it? They do this many times and as long as it is sealed and not disturbed I think it would be fine.
I don't think it is that expensive to remediate the ceiling. People did it all the time in our neighborhood (we would see the remediation trucks and signs up when someone did a remodel). I would get an estimate before making any decisions.
Beth, mom to older DD (8/01) and younger DD (10/06) and always missing Leah (4/22 - 5/1/05)