10 years ago I stenciled my daughters room and now we are tired of it and want to paint over the stencil. Not sure what to do. Do I have to sand, prime etc?

Can I cut the sheen of an eggshell finish with the same color flat?

There are various ceiling areas on the second story (where the wet plaster ceilings have not been replaced with sheet rock). The attic is directly above these peeled paint areas of my 1921 built home. How do I repair?