First, allow me to welcome you to Tropical Fish Keeping forum.
Now to your intended fish. I would not have both angelfish and rainbows in the same tank; there is not space sufficient in this case but aside from that, the activity level of rainbowfish can be disturbing to sedate fish like angels.
The Murray River Rainbowfish, which is the species Melanotaenia fluviatilis, is best in a group of 6-8. Males should attain 4 inches, and females a bit less. So this will be the centerpiece. Some of the medium/large sized characins, rasbora, danio, barbs would be suitable tankmates, keeping in mind the space limitation though.
If you go with angelfish, Pterophyllum scalare, acquire at least 5. A group of 2 or 3 is asking for trouble; 2 will work if they are a mated pair, or both females perhaps, but small numbers of angels almost always results in one or more fish being picked on by the dominant male. In larger groups this normal behaviour is spread out and less likely to target one or two fish--though this can still occur.
No mention is made of substrate, but kuhli loach should be over sand as they must burrow. And at this juncture, I'll mention our fish profile section, under the second tab from the left in the blue bar across the top of the page. If the name is used the same in posts as in the profile, it shades and you can click that as a link to the profile.