Hi billy 69. I am only just starting out with killies myself, so I'm not going to be able to give you a lot of info, but more than glad to share what I can. Check out the pinned thread at the top of this section...something about "mop-spawners". Lots of good info there also.
For the most part, killies are short-lived fish. In the wild they live in areas where the pools they live in tend to dry up seasonally. They have adapted to this by producing eggs which can withstand a certain "dry period", then when the rains come again and the pools are re-filled, the dormant eggs hatch and the next generation of killies is born. This is why, if you check out a fish auction site like aquabid.com, you will see both killies and killie eggs listed, the eggs are very easy to ship and share with other aquarists. This aspect of killie keeping (and the incredible colors!) are what get a lot of people hooked on these fish!
You talk about keeping these fish in a community tank, I have not tried this. I currently have two types of killies, Aphyosemion australe gold, and Aphyosemion sjoestedi (or something like that...also known as blue gularis), they are each kept in their own species tank, both 10 gallons, I have 6 sjo in one tank and 4 aus in the other. I will probably eventually split these up even further to where I only have a pair of each fish to a tank, as I read in a fish magazine recently that rival fish will eat the other fishes eggs. When I bought these fish from my LFS (they were brought in by a local fellow who breeds them), they were all hiding and stressed out, the guy who works there had to move a few rocks for me so that I could even get a look at them. Once I got them home and settled in, with no other fish to bother them, they are out and about constantly and show beautiful colors. So...not saying that you
can't put them in a community tank, but based on my limited observations, they feel better and color up nicer when in a species tank. As far as mixing species,it also seems like I read somewhere that there is a possibility that some species may interbreed, so I wouldn't try it (for instance, both of my fish are Aphyosemion varieties, I would assume there is a good possibility that if I mixed these fish there may be some confused babies)
You also want to be sure that your tank is very well covered, these fish are famous for jumping out of tanks, finding even the smallest opening.
When I first got my fish home, the only thing they would eat was frozen brine shrimp and frozen blood worms. Soon, though, they were eating flakes, small pellets, and freeze dried foods also (I try to give all of my fish a varied diet).
Hope some of this helps you, billy. Keep us posted on what you decide, it's always good to have a few more killie people around. Feel free to pm me if you need anything.