Sorry to be a knit picker, demasoni need to be in large groups like 8-12 or more per species. Malawi set ups should be 1 male to 2 female at least. They don't pair off, they breed with as many of their own females as possible. If not they tend to get nasty. One species per type, hongi and labs are the same labdiochromis species.
My 55g has just acei, hongi SRT and cobue afra about 30 2.5" fish until I ween out the males.
http://www.cichlid-forum.com/articles/compatibility.php
http://www.cichlid-forum.com/articles/p_demasoni.php
Good luck with your Malawis. It take awhile to learn the right combo of cichlids, but it is worth in the end.