You can paint over plaster, but repair any damage to the plaster first, or the paint will crack and bubble. You should also prepare the surface of the plaster to accept paint, which gives your paint job the best chance of looking good and lasting a long time. Before applying the color you want, apply a coat or two of primer. Additionally, use latex paint, and choose a latex paint with a satin finish for areas with dampness, like bathrooms.

Yes, even if you’re being careful, removing tile can damage your drywall to some degree. However, you can minimize the damage done to it by eliminating a majority of the grout and taking your time prying each tile off. Also, it's worth noting that you might have more drywall damages to deal with if your tile is set into the mortar.

Plastering lasts for around 15 to 20 years without needing repairs or maintenance in most cases, and with proper upkeep, plastering can last a lifetime—sometimes more than 100 years. Plaster repair costs between $1 and $3 per square foot, and you may need these services once every 15 to 20 years or so unless you have a harsh climate where humidity changes are a constant issue. You can also opt to skim-coat plaster for between $0.90 and $1.30 per square foot, which may serve you better in the long run.

The time it takes for thinset to dry is determined by your room’s ambient temperature and humidity levels. Assuming the average humidity level is around 40% with an average temperature of 70 degrees Fahrenheit, thinset can dry within 48 hours. Lower temperatures and higher humidity can extend the curing process beyond 72 hours, while high heat and zero humidity can shorten the curing process. However, thinset can crack if it dries too fast.