I think the sand and plants will look just fine. That is how I have mine set up. I guess its each individual taste. I have play sand and a lot of plants. If you are getting Bolivian Rams, they will appreciate the sand more than rocks. They dig small pits for their fry and also shift thru the sand looking for food.

If you get Rams, if you are positive they are male and female then I would stick with 2. They pair for life. I started with 3 and when two of them paired up they beat the crap out of the odd female. Or if they are small, get 3 or 4 and when you get a pair take the odd ones back to the store. The only time my two fight is right before a spawn. Two males will fight each other for territory. Also, if you get Rams, make sure and add a few flat, round rocks to the tank for them. That is what they spawn on.

Not sure about the types of filters you have, but if both have been running and have a good bio load, you should be able to switch them around without messing up your cycle. Just make sure you don't wash the filter media.