A BGK will eat anything that can fit in its mouth, so that rules out guppys/neon/swords/platys/dwarf cichlids etc. Also 200ltrs is not really big enough for a BGK unless you keep it by itself. I have kept a large one (30cm +) in a 200ltr community tank with rams, gouramis and large sword tails but he wasn't really comfortable and could get quite "pushy" with the other inhabitants. If you do decide to get one maybe try to keep it with algae eaters like common plecos and chinese/siamese algae eaters. They are an awesome fish though and mine would eat out of my hand and loved rubbing against me when I was doing maintenance. They have a habit of sucking the eyes off slower moving fish aswell. Also as they do get really large a planted aquarium is out of the question as they require alot of space to move around.
As for filtration if I were you I would try to get a decent canister filter, you can pick up some real good cheap ones on Trademe for the price of 2 hang-on filters. With filtration more is better than not enough.
As far as I know there has never been any proven, documented breeding of BGK's to date, although I did read a story about some guy in Aussie breeding them by keeping them in a tank outside on his porch. They are next to impossible to sex and don't get sexually mature until they reach quite a large size, they do grow to over 50cm in captivity I hear. Also as they use electrical impulses to navigate they should not be housed with other fish of the same species or they muck each others sensors up which causes aggression. If you had a monster sized aquarium (1500ltrs +) it might be possible.
Hope this helps
Jamie.