That is not normal. But I will not kick the sheet rock crew yet.. For I do not know if the floor is level or warped/wavy. If so They could have used a zip saw to cut the contour of the floor into the bottom of the sheet rock before hanging it. Taking the time to do that creates another bigger (to me) problem. The gap would then be at the top along the ceiling and have to be patched and worked to hide which could be a lot of hassles to make it look as it should. I would much rather have the bottom look as your does than have a bad looking,fit and finish along the ceiling. Vapor barrier.. Not needed with Roxul Insulation.Roxul Insulation is very water repellent and does not hold moister like fiberglass insulation does. For it is made of Stone Wool.

Sorry you lost your plaster. Is the gap at the bottom of the wall where the baseboard goes? A gap is normal, 2" is pushing it some. A picture would help.

Spot bonding (and wrong waterproofing) was used on my project a couple years ago. When I asked the contractor about it, they quit. Had to rip out and rebuild with a new contractor. Sorry this is happening to you. Here's what I recommend: Tell contractor to stop work, and that you know spot binding is not allowed by industry standards. Then ask them to come for a meeting on a certain date. Before that date, hire a certified tile professional to come and do an inspection and give you a written report detailing everything that was done wrong and what it will cost to fix it. (Ask them to do a flood test and anything else they need to do to evaluate the waterproofing). Here are 2 organizations with search tools on their websites. www.tile-assn.com Click on “find a contractor” and enter your zip code. Let the miles radius be fairly large, like 50 miles or so. The excellent tile pro that built all my bathrooms was on that site in my area, but about 40 miles away bc he was near downtown and I’m in a suburb. www.ceramictilefoundation.org This site has lots of good information on it. I didn’t find my contractor on this site, but a lot of people have told me that they had luck with it. Here’s where you click to find a contractor: www.ceramictilefoundation.org/find-certified-tile-installers Also, if you are a nerd like me and you like to read, you could download a digital version of the TCNA handbook. It’s less than $40. It’s over 600 pages, but you don’t have to read the whole thing. Read the introduction (about 50 pages) and then read the shower chapters. You can skip all the other chapters such as swimming pools, etc. Reading this helped me to learn about the process and industry standards for water proofing and tile installation; it helped me to ask more informed questions, and helped a lot in my meeting with the contractor who messed up my shower. www.tcnatile.com/products-and-services/publications.html After the pro you hire for the inspection gives you his written report of all the things done wrong, have the business meeting with the contractor at the worksite and discuss all the problems. If it needs to be completely redone, ask them to do that, at their expense. They will either agree, in which case you give them a chance to redo it, or they will refuse, in which case they are effectively quitting. Confirm with them that if they don’t attempt to redo it, they are basically quitting; get them to acknowledge that fact. After the meeting follow up with an email documenting that conversation, and asking for acknowledgement, so that in the future they can’t claim that you illegally fired them. In that email, say something like “We were so disappointed that you decided to quit the project rather than fix the [ list of problems ]. Because we have to have the shower rebuilt, we are requesting a refund in the amount of [$$$] in order for us to hire a new contractor and for the purchase of replacement materials.” They will probably respond to that email to refuse you the refund, but at least then you have an electronic paper trail that shows that you did not fire them illegally, that they quit instead. You can then go to small claims or district court to sue them if you want, but that’s a real PITA. In the scenario where they agree to redo it, give them a chance. Take pictures of the demo process so you can see, and post here, the layers under the tile. If the waterproofing was also done wrong, you’ll need to getbthem to agree to do it right this time. Post here for advice about that discussion and amendment to your contract. Also take pictures twice a day (at lunch break, and in the evening) of every step of the rebuild, including all the supplies and tools. Post them here. When/if they mess it up again (and maybe have the inspector come out a second time), then you can legally fire them in most states. That’s how it is in TX where I am. If you want to know for sure you can look up your states statues online and read the construction laws. If you aren't sure and you don't want to read the laws, just assume that you have to give them a chance to fix first before firing them. After you fire them, ask for a refund and hire a real pro to start over. Consider hiring the person you hired to inspect. Sorry this is happening to you. It happened to me. It's far too common.

Google the installation instructions for your tub, manufacturers will have them documented. There are differences depending on the tub material and the height and shape of the flange. Kohler says if you have a cast iron tub the wallboard should come up to the top of the tub rim/flange leaving a 1/16" gap. Then the tile goes over that and is held back from the deck of the tub by 1/16" gap which is filled with silicone. Today many installers span the junction between the tub rim and the wallboard with a waterproof membrane and something like Kerdifix or mesh tape and a topical membrane speced to span gaps. Your picture looks like the gap is greater than 1/16" and I'm not sure the tub is cast iron. If you have an acrylic tub with a tall, thin flange then the wall board goes over the flange, but must not go down to the deck of the tub, and a bead of silicone is applied between the end of the wallboard and the flange. Then the tile goes on and must end below the wallboard and have a 1/16" gap down to the tub deck which again gets a bead of silicone.