Hi there,
I'll have a shot at this
An initial consideration, tank size apart, is this: part of an Angel's natural diet is Neon Tetras.
The Golden Algae Eaters (aka Chinese Algae Eaters/CAE) can become true terrors as they mature, and their best role as far as I'm concerned is as a tank cleaner/cycler when young. As they get older and larger and start showing aggression they can usually be passed on to a LFS however (I'd be reluctant to curse a friend with them myself at that stage).
The Clowns would probably get a little too large and cramped, and there is no way round that really, as yes, you would need a few.
The only other teeny bit of advise I could give is re: the Guppies; generally they do better with a higher female to male ratio (2-3 females for each male).
Beyond that, you might be pushing it a bit stocking wise, especially when the Angels got to be adults...
For the sake of health and a sustainable level of maintenance I'd say:
- 8 Guppies : 2 males, 6 females (even if that means a bit of shuffling with what you currently have)
- 5 Neons (you could get away with adding a couple more to "flesh out" the school even)
- 2 Dwarf Gouramis (a pair

)
- Maybe a Bristlenose or some Corys to cover the bottom feeder gap left by the CAEs/Loaches
I'm sure others will have their own views on this too
From my own experience, that would be a nice, peaceful community, with plenty of interest and so long as you have appropriate filtration, the maintenance schedule wouldn't be anything out of the ordinary.
You'd have your schooling covered with the Neons, plenty of action with the Guppies, personality on the bottom from the cat(s) and the added bonus of the possibility to see the Gouramis go through their nest building etc
Good luck with it all,
Dex