Definitely get them neutered. I had a lone male, and last year I got him companions. two brothers. They had not been neutered. The first day I had them, off to the vet they went for wellness checks and the old snip. Since we had the thirty-day quarantine to go through, that gave them a chance to heal and to get rid of all the male hormones -- not to mention the smell. The only thing stinkier than an intact male would be two intact males!

Now I have three neutered boys living together, thick as thieves and happy as can be.
For introductions, read this:
http://www.sugarglider.com/gliderpedia/index.asp?Introductions
Good luck!