I probably wouldn't do the guppies. Firemouths aren't piscivorus by nature, but like most fish, are opportunistic, and may see your guppies as snacks. I've never tried to keep rams with anything else, but I'b be a bit worried about water parameters, as rams typically prefer softer, somewhat more acidic water than many other cichlid species. Also, I would recommend only 1 species of ram if you decide to go with them, unless you get all male or all female, to prevent hybridization. The gouramis may get beaten up; firemouths aren't as aggressive as some cichlids, but they have their moments. Some pet stores recommend firemouths as community fish, but I disagree. The same with the Odessa barbs; they're very cool looking fish, but a bit small to hold their own with cichlids. IMO, and it's only an opinion, mind you; either go with a community tank, or a cichlid tank. The 2 don't always mix well.