Get the most filtration you can get for cichlids- they are messy, as others have said. I'm a fan of canister filters myself (have a Filstar XP3, rated at 350gph on my 90 gallon Afrcians tank), but I have used an Emperor 400 in the past when the tank had less fish. I don't think surface agitation is a big deal for cichlids. Mine never seemed to care, either way. The bio-wheels eventually seem to get rather "sticky" and not turn as freely. People are right that you don't have to use the Marineland cartridges (or if you do, not replace them as often as Marineland would have you believe). Filter material can be tied on or the cartidges themselves can be (carefully) cleaned under good, strong, running water a number times before they shred enough to warrant replacing.
Plants- can be tough with cichlids. They will uproot, eat, shred most plants. I have an anubias and some Java fern in my tank that are doing ok, but those are pretty tough and the fish don't seem to find them tasty. That said, plants are not a big part of the natural habitat of Africans, anyway. There are some, but not like a rainforest or other habitat. Make sure you have enough rockwork forming caves and hiding holes. Cichlids can be aggressive- check that, cichlids are aggressive and some chasing and such is normal, but if you don't give them place to run to, you could easily see lots of ripped fins and unhappy fish.
As for other fish to put in with cichlids, syndontis catfish are the usual choice, as they are natural to the habitat. You need to be careful, again because of the aggressive nature of cichlids. Over the years, I have kept a pleco in there, and a couple of clown loaches and a few other things. Right now, the tank is all Africans.
Here's an older pic of the tank:
http://thirtytwopaws.com/fish/90_Gallon_April2002.htm
The rockwork has been redone (several times) since then, but that's the basic idea. And that is the Emperor filter in there. No plants at that time. And the fish have changed to some degree, also.