I’m in Canada and the townhome we just bought used “master bedroom” and ”second bedroom”. The bathroom is actually “master bathroom” too, though en-suite is more popular. I think “principal bedroom” works well, especially if describing short term rentals (where multiple couples might share a rental), rentals by you adults (again where roommates might be sharing), or multi- generational homes. You still want to confirm which room is the largest, but there isn’t a need to explain who then “master” of the home is. Random point- when I’ve booked Airline tickets for my son, he always gets the prefix “master” vs “Mr” on his tickets/booking. Hubby and I always get a good laugh, as there are definitely days where it feels like he runs things in our home! Maybe he should get the new master bedroom haha.

I like my first idea best as far as use of space. I know people say not to put toilets on an outside wall. We had one in our last house in Iowa, but we had 2X6 construction. I don't know how high your window is, but I'm guessing the toilet would fit under there. The shower would be 5 feet long or shorter if you want a wider space to get to the toilet. (kind of tight the way I have drawn). You could do a 5 and half foot long shower and do an angled door at the left end to allow room between the shower and toilet. The vanity would be about 7 feet long, unless you do a 60 inch vanity with a linen cabinet at the door. I would reverse entry door swing if you do that.. The second top right could work and you would still have a small closet. The bottom left plan would require waterproofing your front window. Hopefully someone will give you other ideas. The bottom right plan is bigger, but no closet. Each square equals 1 foot.

Depends on your skill level. How are experienced are with demo, framing, drywall, spackling, trim work, etc? If you are getting a bank loan it may be against the loan agreements. Your building dept may not allow it as you wioll more than likely need permits and a C of O. As you mention electrical work would need an electrician. Realistically if you need to ask if this would be DIY'able it probably is really not a good idea to attempt.

Oh, boy. That doesn't seem fair at all...two water leaks so close together. This is not the time of year I'd want the interruption, inconvenience of a contractor in the house. Not that I can think of a good time of year for that. I hope you find something lovely that makes you really happy for a flooring product replacement. So - chin up, facing forward....you've had worse times in your life and can do this. Maybe you could even get your daughter to take you in with the dog for a couple of weeks and she could feed you too 😂