We have old double hung windows that were excessively caulked and painted shut. On the inside the caulk is mildewed, ugly and spread too far on to the window panes. I want to; #1 remove and replace the old caulk around the glass, #2 repaint the inside wood and #3 fill a crack between upper and lower window. Windows will never be opened. Replacement windows are not an option. I have very limited skills but lots of time and tenacity.
I would suggest purchasing Jasco paint remover which will not harm the glass… but don't get it on anything else including your skin! Once you have removed the failing caulking and paint. I would carefully mask off all adjacent surfaces, prime, caulk and paint with a high quality acrylic paint in either satin or semi gloss.
Another option for masking windows, which is a little more costly would be to use Jasco Liquid Mask instead of tape for. You will spend about $50 bucks for a gallon but you will save a significant amount of time by not having to mask all those window panes, as well you will end up very professional results!