Figuring out a hole is easy. What I want to know is why in the hell do you have water pipes in an attic that can freeze? Get the pipes out of the attic.

Sorry I live in Canada and water pipes in the attic space or in outside wall space is not accepted

Don't bother fixing the ceiling until you get rid of water pipes unless you like a redo every year.

My guess is water damage from leaks around the doors and from the carpet. IF the plywood is still ok( not spongy) then for now reseal the doors and lay some vinyl plank floor. Not ideal but from what I see you will be ok until the gut job which this bath needs.

As long as the drain is good and no leaks from shower controls a little silicone and cheap vinyl floor should smooth you over til gut time

For sure do re-bar in concrete. But its the base under it that makes the difference on longevity. Done right concrete should last way better than asphalt

Um I have done a lot of basement bathrooms on newer houses that had all these "rough ins" That is what they are Rough ins for a bathroom.

Problem is they are never where the home owner wants the bathroom so we end up jack hammering the floor up to move all the pipes.

If you are good with the layout then building a bathroom is easy. But if you want to move shit then busting concrete is in your future

One rule off rough framing. Bigger is better. It's easier to add then subtract.

Eg: When I frame a door opening for say a 30 inch x 80 inch door the RSO (rough stud opening) is 2 1/2 wider and 2 1/2 inches higher. This gives you room to shim your door jambs perfect.

The number one fails I see of DIY is trying to frame RSO tight. Not how it's done.

Now bi folds can be a little tricky. Follow the instructions for your finished opening but the concept is the same

You need quarter round against all the base as well as the door. Now of course typical Quarter round isn't wide enough so you have to be creative with a build out at the door so the quarter round goes straight thru and covers the gap. What you need here us an oscillating tool, table saw and an air nailer and a tube of painters caulk.

The trick here is building out from the door thresh hold even with the base. A couple of ways of doing it.

You can rip a piece of whatever the width from door threshhold from base to base and carve it around the angled casing or cut the casing with the oscillating tool and slide the buildout under. nail that down then run the quarter round thru.

Sorry if I make no sense. I'm a doer not a teacher. I look at your problem and in my head with my tools it's an easy fix.

You rip it all out. Redo with tile backer/ cement board and use red guard or equivalent.

Bathroom renos are expensive for a reason. It costs money to do it right but right is the only way around a tub. Same with your shower controls. Do not cheap out. Most plumbers I know will refuse to do tub/ shower controls unless they are Moen. Not to say others aren't good but Moen is the least problematic if issues arise down the road.

Then there is the framing. Ripping it back to studs allows you to shim any wonky studs to make your backer nice and even which in turn will make your tile job easier and nicer. Don't do half a job or you will be sorry

Silicone. Pretty standard way for most bathroom sinks

We did back in the 80's. There were smoking seats at the back. Thing is I got one first row back of non smoking. I lit up but soon realized dude in front was non smoker.I put it out and never smoked on a plane again out of respect. Of course it was banned shortly after but you are right. What cunt smokes on a plane? I will go without a smoke before ever jeopardizing a plane.. Some are cunts tho.

Just use a hammer and a cold chisel. usually one good smack knocks them out. Leaves a hole that any quick drying concrete patch will fix

You can buy a grinder and grind off but you will still have patching to do from the grinder. hammer and cold chisel always works for me for tack strip nails

Not too shabby for a first go. Nice job. Good luck on the many other projects that come with owning a home

Top quality Sherwin Williams exterior covers excellent on one coat. If needed do a second light coat.

And no a quality paint is the coating.. Factory preprimed wood( or whatever) should hold up really good with any quality paint

So simple. If you are facing door and pushing it open then knob on left and hinges right then it's a rh swing. The heft/right swing is always determined my the side you push the door open

Pretty simple. Go to HD and get a can of stain and polyurethane in one. One coat and done easy.