Tank advice for Labidochromis caeruleus

Hello,

I've been keeping fish for years in various cities (i.e. various water
conditions). I did Severums, marine fish, and kribs in a plant tank.
In my last move I got rid of all my equipment. Now I'm living in a new
town with hard water and I got a free 55g tank from a neighbor. I got
a HOT Magnum/Biowheel system for filtration, Ebo Jager 150W heater,
and the tank had a glass cover.

My water turned out to be GH 12-13, KH 10-11, and PH 7.5-8. So I'm
thinking african cichlids. I don't want fish that will get too big or
overly aggressive, so I have settled on Labidochromis caeruleus
(a.k.a. electric yellow mbuna, etc.). Other suggestions would be
appreciated.

My questions are this:
How much and what color light should I go with? And is there a cheap
way to do it (e.g. shop lights)?
What substrate/rocks should I use. I know they want a big pile with
lots of caves and hidey holes, so what would be appropriate (e.g.
cheap, non contaminating, not too heavy for the tank, look good with
yellow fish, etc.)?

And any other tips on keeping these guys (other fish that might go
with them, etc.) would be appreciated.

Thanks,
--Todd