Yes you can. You must first paint over the old plaster with a product such as Eucoweld, which chemically adheres the new plaster to the old.
Yes you can plaster over old plaster. There are some primers that will assist adhesion, but I've never had a problem leaving them out and just applying slightly wetter plaster.
No, you plaster or mud it first.
lath and mortar walls and ceilings have a greater flexibility than standard plaster. If you do plaster over it you firstly need to be very confident that the old mortar is sound and fully adhered to the lath. You would also have to seal the ceiling well to stop the water in the plaster from literally being sucked out of the plaster. Regarding tiles. If you are thing about ceramic tile then NO!. The weight of the tiles would pull the mortar from the lath with great ease. It is defiantly better to either plasterboard directly to the old ceiling and using dry wall screws NOT NAILS screw directly to the joist not the late you can then put a good scrim tale over the joints and plaster accordingly. The very best option however, is ...............drop the old ceiling, re-board and plaster
Asbestos used to be used in the plaster mix to help strengthen the plaster. So if you are ever renovating an old pool with plaster it is best to have it tested for Asbestos.
Depending on what the plaster surface damage is to the pool, it really is pretty easy to repair the plaster on your pool. You just need a chisel, or a small angle grinder if you are really handy, a hammer, a trowel, some water and a sponge. they sell pool patch kits for all the pool surfaces. look for pool plaster patch kits and you will find an easy to use solution.
No
Over Your Head - 2006 A Pain in the Plaster - 2.26 was released on: USA: 29 December 2007
If you put plaster over a water balloon and freeze it, the water balloon will bulge out.
The finish plaster is normally white all the way through. It sounds like you are dealing with a pool that has been replastered by the method of putting a "brown coat"/"scratch coat" (the gray plaster you noted) over the original finish plaster surface, and a new finish coat of white plaster on top of that. The scratch coat more like a thin concrete than plaster (doesn't have the white marble dust in it) and is used to get a better bond to the old surface.
Over Your Head - 2006 A Pain in the Plaster 2-26 was released on: USA: 29 December 2007
Over Your Head - 2006 The Disaster of Plaster 2-39 was released on: USA: 28 June 2008
No, the plaster can be patched. But how good the patch looks depends on several things like the color of the plaster, its age, and the person doing the patching. New, white plaster would be the easiest to patch while old, colored plaster would be more difficult to do satisfactorily.
Not very stylish or modern, but its possible to do. Enjoy your project.