If you are really perfectionist types but don't want to pay a painter, maybe try to find a drywaller just to come and do those repairs. If he's only there under and hour it may not even cost more than 100 dollars. 6 estimates is too many to get when you are looking for painters. Try asking friends if they know any that did work for them. That is the best way. Yes, painting is a loser a job that anyone can do, but still these guys at least want to make a living, even though it may not be enough to raise a family and all this, they still want to pay the rent. There are however rip off contractors and gougers out there too so I understand that and this is true of any business. Anyway, what I do with drywall repairs when there is tape coming loose is this: first, I address the repair and decide if I want to use mesh tape or real drywall tape. Mesh tape is easier for a DIY'er because it will stick by itself because it has adhesive on it. Drywall tape has to be embedded into a layer of wet drywall mud. I would buy both at the store and use what you like best...both are cheap. First, you cut out the failing tape with a very sharp utility knife. I always make sure to make the cut perfect and totally through the paper so that when you pull on it to remove it you don't end up pulling out a bunch more than you want. If it is a seam in the center of a wall or ceiling, it's easy to just cut out the bad, then sand the area to remove any debris, use a drywall knife/blade to fill the area with drywall mud, and then embed the tape into that and skim over lightly. This will be your first coat. After this is dry, you can lightly sand again and lay on another coat of mud. Remember that the tape is sitting on top of the drywall, unless there is a real seam there, so you may need to 'float' the drywall mud over the top of that tape to disguise that there is a hump there. This is where the pro really shines and the homeowners get lost because they may put way too much mud on and then have to sand forever to get it all smooth and of course it rarely comes out looking perfect. Just keep in mind that whatever mud you are applying, this will need to be sanded and sanding creates dust and isn't a very fun job so the idea is to minimize the sanding step if you can by applying the mud properly. If the failing tape is in a corner, sometimes I may just use my utility knife to cut out just the portion that is failing and then just fill that with mud and skip the taping step entirely. It depends on the size of the repair and the integrity of the tape. Every repair is different. Also, there is no guarantee that the tape will never fail again. If there is movement behind the wall in the studs (which there always is) any repairs you do can come back and you may have to do them again. Every house has these recurring nail pops, cracks, etc. where even if the repairs are done perfectly, they can still return. Some repairs do stay repaired forever though. It just depends on a bunch of factors as always. Good luck!

Unless there are layers of glue-applied wallpaper to remove, it's uneconomic to r&r drywall rather than repairing it. Electricians are masters at fishing new wires where needed. Plus, what your estimate is missing is that the old smash- and-shovel-it approach is no longer prudent or, in many cases, allowed, when it comes to removing lead painted drywall. (Though you'll likely soon hear from someone who says, "lead, schmead, so what's a little dust gonna do ya?") Here is a link that might be useful: What Home Owners Should Know about Lead-based Paint

I'm not a professional and it depends on the size of the area to be repaired, but it's pretty easy to cut out damaged dry wall and then mud the patch seams. You want to do whatever will maximize the clean, level surface. And, yes, you will need to feather and sand your mud until it is dead level. I wouldn't paint the mudded, repaired drywall before tiling, at least, I never have. And I've never primed drywall before mudding it. If you've only read or watched videos, be sure you practice. If your repair area is large, even if just 'paper', maybe hire somebody?

It's not uncommon to find bathroom walls build mostly of wire and plaster in turn of the century multi-unit housing. Evidently itwas an approved practice back then because the resulting wall was essentially fireproof. And, having had to tear a few of them out, I can attest that the resulting wall is pretty darn strong. So, there is nothing wrong with just rebuilding the wall using the same wire and plaster method. But, have a chat with your building inspector first to make sure the rebuild would be approved. If I recall correctly, the method was to stretch wire mesh tautly from floor to ceiling and side to side,, attaching it on all four sides. The applying a thick brown coat, then the scratch coat over that. Since the tile was mud set, a final smooth top coat was not necessary. However, since your tile would be thin set, a smooth and level top coat would be required. There is a special reinforced structural plaster used as the brown and scratch coats, and I don't recall at the moment what it is called, but your local supplier should know. As a shortcut alternative, if you have the room, you could screw and glue 1/2" exterior ply to whatever is left of the old wall for structural support and tile over that. My preference, however, would be to rebuild the original wall. For waterproofing, apply Schlüter Kerdi cloth to the fully cured plaster, (or plywood) then tile over the Kerdi cloth according to Schlüter's instructions.