That’s awesome that you are moving towards making a career out this! There is definitely a shortage of competent, educated & skilled labor out there. You will find that bathroom remodeling will be easy to advertise and obtain clients. The showers and tile designs somewhat sell themselves, plus it is pretty much the most expensive and labor intensive square footage in a home. And everyone has 2 or bathrooms, so good chance of repeat business!
you are right, trade schools will get give you an overview, but nothing specific. I went to trade school as well 20 years ago. So many more resources online since then! Which is one of the reasons I teamed up with Jeff, to demonstrate and show others how to remodel bathrooms, giving back because so many others have helped me out over the years.
So to your questions. It really depends on the manufactures recommendations. If the tub can be installed with mortar, then I go that route. It really gives the best support for a tub and gives it a solid feel. The Bootz tub had a foam base that does not recommend mortar. Pretty much set it in place and mount to studs with fender washers. And the way its mounted to studs are also in manufactures specs
You always want to follow the manufactures specs so that the warranties are held up.
Look forward to seeing and helping out with your projects! Crazy people would layer over 3 or 4 times, lol!