I can answer these questions for you....
they fit in really well with a community tank. They can tolerate a wide range of parameters. But some killis have relatively large mouths compared to other fish, so keeping them with shrimp is not advised.
Breeding is super easy. Killis are prolific breeders. I just place a suitable pair into a breeder box with a spawn mop (made out of knitting wool), and feed lots of food-live or frozen. They will do the rest. Adult killis are not fussy eaters.
Some species are easier to care for the eggs than other species. Beginners should avoid the peat spawners. Non peat spawners eggs can be left in water, and the egg will hatch in 2-3 weeks. I remove the mop and place it in an ice cream tub.
Care for fry is like any other egg layer. Baby brine shrimp, vinegar eels, micro worms are all suitable. They will readily take powdered fish food when they are bigger.
Beginner species would be any killi that is non annuals, non peat spawners.
Fundulopanchax gardneri Nsukka, and Aphyosemion bitaeniatum are two species I have and are considered easy to keep. Check out some pics in the killis section of SKF.
i have just spawned a batch of fry for both, and I'm now over stocked.
I'm more than happy to sell you a few pairs to you, just send me a PM.
I want so many other killi species, but just don't have tanks for them.