I am working with my 2nd dog now in formal training classes. I plan on having more in the future, and every one of them will go through classes. I always learn something new every class I take, even if I have done the class before. A couple of times now, I have repeated a class just so that I could get a better handle on how to do it right.
Dogs (Rotti's in particular) are very smart, and pick up on all kinds of signals that we don not even know we are doing. Having a person on the outisde looking in, helps to point out these things.
As for the space, I live in about 1,000 square feet (in a basement) with 2 large dogs. It can be done, but you will have to make a few adjustments, like daily walks and such.
Good luck, and keep us informed as to how it goes!!