RE: Sail quiver: One or more manufacturers?
Personally, I use two different sets of sails: one for wave, one for slalom/blasting. Each set of sails are same manufacturer and model (Ezzy Wave LE and Maui Sails TR2).
Should I substitute one set, I would purchase the new one in the same way: same model. This way, I get consistency of character throughout the quiver and easier tune learning.
As for the masts, I check with both sail and mast manufacturer for compliance and I assume no risk in this area.