We recommend uHeat for Underfloor Heating Systems, and The Wetroom Store for all things bathrooms and wetrooms. They provide discounts for forum members.
Welcome to the forum. Although you can post in any forum, the USA forum is here in case of local regs or laws
When looking for plumbing courses, please always try to go visit the training centre before parting money. Don't use a credit agency to pay for your training (something dodgy companies do) and never deal with salesmen on commission. Always speak to the actual tutors of the training establishment.
Some online courses are genuine, but a lot are not and will not provide you with the right qualifications for the right plumbing job you want.
We recommend City Plumbing Supplies, BES, and Plumbing Superstore for all plumbing supplies.