Well this is where you'll get varying opinions. What has worked for me and what I prefer may not be the case for someone else.
I would stick with either one big filter like an FX5 or two smaller filters like fluval 405's or rena xp3's.
As far as fish... stick with the same type. If you go with haps, stick with haps. Peacocks, stick with peacocks. Mbuna, stick with mbuna. Haps and peacocks work better together than mbuna and peacocks or mbuna and haps. They have varying levels of agression and the peacocks and haps are generally a little more mild mannered.