Some rams can be touchy towards water conditions... mainly those bought in pet stores (most of which are asian bred) need soft acidic water or many of them waste away. If you can, try to get european bred rams (locally bred rams are also another excellent option), they tend to be hardier and used to most of the pH's found in tap water. I would check your pH and your hardness.
It would be best to get a m/f pair, same sex pairs may litterally kill each other. A 10g, IME is the minimum tank size although larger is better, especially for more tank mate options.
Rams aren't always "peaceful", for the most part they stick to themselves in their own territory but may defend it fiercly. Breeding pairs can be royal terrors as they defend their eggs/fry. Since they are active daytime bottom dwellers, I personally would avoid cories (unless you have a good size tank, say one with a larger footprint than a 20g long) to begin with as they share the same space and the cories really can't get away from them as they aren't really good at hiding. Kuhli loaches and oto cats are probably better choices as both species are not seen as large of a threat (kuhli loaches hide under decor or plants during the day and otos don't move much and are mostly active at night).
Most smaller tetras, such as glowlights or cardinals make good tank mates as well. I would avoid neons as they should not be kept in water warmer than about 78F while rams really should be kept in water of 82F-86F.
If you can't get anything but pet store bought rams and your pH/hardness is quite a ways from 'ideal', I would take an hour or more to slowly acclimate them to your water (take about a half a cup of water and dump it into their bag every 5-10 minutes once water temperatures have become close or equal to each other).
HTH
Puma