Hi - am doing a basic update of a small bathroom, and are replacing some water-damaged drywall (the builders did not use moisture-resistant) above the shower but wish to keep other parts which are perfectly sound, but I want to tile over these parts, basically, I plan to tile the wall where the shower is, and wonder if I absolutely have to stay with the metal drywall corner strip considering I will tile over it. I intend to use some sort of waterproofing under the tiles/over the drywall, either the sheeting stuff or the paint-on stuff...so wonder if I need the metal corner piece or if I'd be better removing it. Like I said, I don't want to disturb the sound drywall, but around the shower they used 1/4" furring under the original drywall to allow for the thickness of the shower lip, but I would ideally like to use 1/8" furring (which is closer to the true thickness of the shower lip) because I don't want the tiles sticking over the edge of the top part of the shower more than is necessary, and the 1/4" stuff will make a considerable difference.

Other question is, I am considering tiling the ceiling immediately above the shower enclosure, the drywall extends up about a foot above the shower cubicle, and the ceiling space immediately above is around 3'x'3 or 9 sq ft. The ceiling is, I presume, regular drywall but is more or less in perfect condition so I don't really want to replace it but could at least just where the tiles are going if necessary.

Any suggestions/feedback on how you think this would look, is it too weird, and what sort of adhesive and technique to use? I have a sturdy camera tripod and was considering using this to hold up a brace/flat sheet to hold the tiles in place whilst they set, if necessary.

Lastly, previous folks did not put plastic moisture barrier under the drywall except where the shower is against an outside wall, then they forgot to use moisture/air barrier in the corner which is a false wall that sets back from another outside wall (ie shower is in a corner) - I don't have much access into that area where there's no moisture barrier but was considering putting plastic under all the drywall at the top of the shower cabinet, and maybe allowing some overlap so it tucks between the drywall and the shower lip, so it drains back to the shower lip (although if I silicone the transition between the tiles and the shower itself, moisture would have nowhere to go - does this sound like a good plan?