Get a good respirator and wear it when you are removing the tile and grout! Recently, I removed the dried grout from a small tile sample board with a hand grout saw ( in order to try another color of grout), and then when I went inside to mix up the grout, I noticed these horrible warnings on the grout package about not breathing the silica dust in the grout and how it can cause deadly silicosis and lung cancer, etc! Afterwards, I ended up with such a terrible hacking cough that lasted for over a month from breathing even just that little bit of grout dust. I hope I didn't permanently damage my lungs. Hope this helps you!

This sounds like efflorescence growth from water passing through the grout in the tile. Ask your builder what type of grout he used - was it regular grout or epoxy grout. Regular grout will allow water to permeate and any place this happens you can get this efflorescence scale forming. Clean it with 3-1 muriatic acid and an acid brush. Apply full strength vinegar once per week and scrub with a pool brush to limit its return.

A few points. A competent general contractor will have sub contractors do things to minimize the dust and debris. They will all say it it difficult to eliminate 100% of it, but the better ones come close. Some general things that come to mind immediately, based on your brief description are 1) seal off individual rooms, using plastic sheating and tape, 2.) do all cutting outside, 3.) clean up at the end of each and every day, -- I'll emphasize meticulously clean up everything, at the end of any day no debris or demolition materials left inside, and any debris, cuttings or sawdust created outside in a driveway or parking lot are cleaned up daily (not the next morning). If they are not doing 2.) then quickly find another CG. Nos 1 & 3 are standard, and the degree to which they do this is a measure of their workmanship. If you have any type of forced air heating or cooling then get a full duct cleaning after all the work is complete. And of course change air filters after the cleaning.

He is no tile pro. Or anything else. You knew that. You still hired him. From this, it’s doubtful that he got the new to him system done correctly either. It’s not just the grout.He is clearly out of his depth on any tile job.