Good companions for keyhole cichlids??

#2
I would leave the keyholes as the only cichlids in the tank. They may be the most peaceful cichlid out there but they're still cichlids and can show aggression when they feel their personal space is being invaded.
Cories and/or tetras would make nice tankmates. Panda cories don't get too big and look a bit similar to the keyholes withe the creamy tan coloration and dark spots.
Black phantom tetras are nice shoalers and aren't nippy. Big enough to not get eaten. Males are he more popular for being a dark overall color and having long dorsal and anal fins but the females are my favorite since they have a nice amber color and any black on them only compliments it. They fill out when ripe and look quite jolly and are opped off by cherry red ventral fins. I found them incredibly attractive and the perfect compliment to my own tank with keyholes.
 

#7
Mine haven't spawned yet and I'm not really trying to get them to but if it happens, cool.
They need a flat spawning substrate, they might dig a pit in the substrate or use a flat smooth rock. Soft water is needed for successful hatching and rising of the fry. They can be a little difficult to deal with, is what I've read.
 

#9
No. Quite usually with most cichlids age and practive effects amount of eggs and fertility as well as how well the pair has been conditioned prior to spawning.
The first few tries may be low in egg-count and unsuccessful as they might not get fertilization right the first time and the eggs will consequently be eaten by the parents. Practice makes perfect though and the more they try the higher the egg count and more successful the fertilization rate.
Keyholes are also quite difficult to sex as there aren't any obvious dimorphic characteristic between them. A male may be just a bit larger than a female and have longer extentions to the dorsal, anal and pelvic fins. :)