Two questions:Fish compatibility and identifying something I found

Hey /r/Aquariums , I've got two quick questions that hopefully you can help me with? The first is, I have recently started a cichlid tank (25 gallons) and I was wondering if a yellow lab, kenyii, and blue mbuna (I think) would be compatible with an oscar? I know they require different water types in the wild, but I'd assume they're farm raised?

Second question: I'm finding these weird white/yellow cysts of some sort on my tank walls, some plants, and even on my mystery snail's shell. I'm not really sure what they are. I've seen the mystery snails lay eggs before, and those were pink wads of bubbles, but these are singular 'grains'. I did add some horned neerite snails ages ago, but I believed them all to have died off (found a few empty shells). Maybe they didn't and they're laying eggs? Pic attached, sorry for the poor lighting. http://imgur.com/vMSN9

Edited to say these are two different tanks. Just to clarify.

Final edit: Alright, I'm taking the oscar back to the store. Sorry to cause a fuss, folks who fussed. Thanks for your advice, those who advised. I took what I was told at the fish store at face value, made the purchase, then began to have my doubts. Thank you guys for setting me straight. While it's too late to return the African cichlids, the Oscar will go back to the store, where hopefully somebody who can give them proper care will buy him.