For a clean-up crew I prefer a variety of snails + the normal population of pods/worms/snails that come-in on the the live rock. Some like hermits as well, but I'm not a big fan (little troublemakers IME).
As for fish...
A pair of clowns and the P. fridmani (or a pair) are good, reef safe choices. Several types of clowns and the fridmanis are available captive raised and very hardy.
As for the sleeper gobies (Valenciennea genus) - I don't have first hand experience there (I generally avoid digging fish). One downside to any digging species is the mess they make getting sand on clams/corals in the lower parts of the aquarium. With the sleepers, however, they also have a reputation of being difficult to keep alive long-term as they can apparently starve once they've depleted the sand bed of infauna. Your best bet would probably be to look into another genus - there are a lot of great, reef safe gobies. If you're interested in shrimp (as mentioned), you might look into some of the gobies that live with a symbiont shrimp species.
Flame angels, as with most Centropyge angels are hit/miss with many corals, although there are some it probably would take no interest in (some soft corals come to mind). In general C. argi (Cherub Angel) and C. acanthrops (Flameback Angel) are considered the most reef safe of the dwarf angels.
As for aggression/compatibility with each other - I don't see any big problems with the group you're thinking of.
Some good beginners corals would include such soft corals as mushrooms, zoanthids, star polyps, etc. Not the easiest corals to get rid of later, however, if need be (do a search). :wink:
Anyway, that's my $0.02...HTH