Can two or more different models of Yongnuo flash work together?

I have a Yongnuo YN-568EX flash and I use it with a Nikon D7100.

If I buy another two more Yongnuo flashes of any model other than a YN-568EX, in principle will they all work together using at least one of the many types of setup?

If the answer is yes, does the same apply to different models from another brand? e.g. Could you use a Nikon SB-900 and SB-700 together off of the same camera?