Hey,
Discus are still not going to be a good choice. Your friends tank must have a proven spawning pair of Discus. Angels and Discus will not mix well in a small tank, and neither will Discus and Rams. If you want Discus it will need to be a species only tank, with maybe a shoal of bigger tetras that won't get eaten (Red Eye for example.) You could also sneak in a shoal of Corydora if you wanted, but they would have to be sterbai. Again, as mentioned, most Pleco with try to get a taste of the slime coat on the Discus, and personally I wouldn't put a Pleco anywhere near my Discus. Don't know if the dimensions where already listed, but what are they? If you want Discus, this would be a good stock:
5 Discus
6 Red Eye/Black Skirt etc.
4 Corydora sterbai
The only thing I could suggest to you, if you want Discus, Angelfish, Ram, Dwarf Gourami etc. etc. is to get a bigger tank.
Discus are still not going to be a good choice. Your friends tank must have a proven spawning pair of Discus. Angels and Discus will not mix well in a small tank, and neither will Discus and Rams. If you want Discus it will need to be a species only tank, with maybe a shoal of bigger tetras that won't get eaten (Red Eye for example.) You could also sneak in a shoal of Corydora if you wanted, but they would have to be sterbai. Again, as mentioned, most Pleco with try to get a taste of the slime coat on the Discus, and personally I wouldn't put a Pleco anywhere near my Discus. Don't know if the dimensions where already listed, but what are they? If you want Discus, this would be a good stock:
5 Discus
6 Red Eye/Black Skirt etc.
4 Corydora sterbai
The only thing I could suggest to you, if you want Discus, Angelfish, Ram, Dwarf Gourami etc. etc. is to get a bigger tank.
my friends tank (with the Discus pair) is bigger than mine *sigh* there goes my hopes of having a pair of Discus just yet 
They avoid each other like the plague, Vera, the female just hangs around with my female platys! I love all the different types of tetra, i just keep the black Phantom and Black Skirt typs. The Phantom ones have got a gash of neon on their sides which looks cool. Britlenose plecs get to about 4-6 inches so not too big and i think, golden nugget plecs get to about 8 inches and peppermint plecs get to around 7 inches. You have loads of scope with all the different types of plecs, these are just my favourites, so if you went for a smaller variety like one of these, they would make a great community tank mate. Hope that helps! GRJ. 
/www.thinkfish.co.uk/
my BF is starting to worry that the fish my get more attention than him soon
at the moment so I have alot more time during the day while I am at work to get on the forum