Don’t remove asbestos and lead without proper remediation procedures. You’ll likely have both for that. Get some training before you ruin your health. https://www.epa.gov/lead/renovation-repair-and-painting-program-training-providers

They only inspect the visible surface. Not what is inevitably underneath. Learn. Or you’re going to end up sick. A fresh coat of paint over lead paint will not test positive. Until you tear that wall out, or sand it down. Very positively Lead Dust. Same with asbestos. As soon as you touch anything, you have issues. So you live your life never touching a thing. Or you learn how to do it properly. You don’t ignore the inevitable contamination and risk your health.

There shouldn't be any asbestos in a fiberboard ceiling and it is highly doubtful that anyone painted the ceilings with lead paint. A $10 test kit will prove that. It will be very easy to remove and replace with gypsum board. Typically there is wood strapping above that should be spaced to allow full sheets to be installed. You'll have to pull a lot of staples or hammer them in. You'll have an opportunity to make electrical/plumbing inspection/changes when the ceiling is open. Make sure you don't cover up junction boxes, etc.

I have a 50s model mobile home with what appears to be fiberboard stuff.would there be asbestos in it?