The terms ghost and glass shrimp are a catch-all name for many species of clear shrimp, so them looking a bit different from each other is pretty normal. The only concern is if you get one with long arms and blue claws, as that is actually juvenile predatory prawn, and will get pretty darn big and hunt other shrimp and fish. I've gotten them twice from major chain stores, and they can get mixed in pretty often. The good news is that you can house them separately and grow them to eatin' size! ;)
Ghost shrimp are not biofilm or algae eaters. What this means is that they pretty much just eat uneaten fish food and dead animals in the tank. They may also eat microbes and occasionally catch and eat smaller invertebrates in the tank like baby snails and copepods.
They don't have a very high bioload, and can be kept in the numbers suggested above (10 per gallon) for tanks 30 gallons and under. Generally for a standard 10 gallon tank I suggest 5 per gallon or less, unless heavily planted to provide foraging space.Tanks 35-75 gallons can house 15 shrimp per gallon, and tanks larger than 75 can generally house 20 ghost shrimp per gallon, provided proper filtration is provided.
RCS are biofilm eaters, and I believe they will also feast on diatoms and some types of aquatic fungus. They have very low bioloads, and can be kept in high numbers, though it's not suggested to pack them in tightly.
A good max point is 15 shrimp per gallon for tanks 15-30 gallons. I normally suggest less than 5 shrimp per gallon for tanks that are standard 10g size, as there's not much floorspace, and these guys breed very quickly. Because RCS are mainly biofilm eaters, they need a lot of foraging space, so if you only plan to be low or moderately planted (low planted is 20-30 plants of moderate size), reduce the number accordingly.
I don't know what your whole tank looks like, but judging from your photo I'm going to go with the assumption that it's very lightly planted. In this case you'll want to go with ghost shrimp, and not cherries, since you may not have enough biofilm for the cherries and will end up needing to feed them additionally. you'd be fine adding two more per side, but you can probably go as high as 10-15 per half. I'd just get a handful more (2-5) as they will actually breed and fill in pretty quick.
I had 20 gallon guppy breeding tank that started out with 10 ghost shrimp and ended with about ~400 or so by the end of the summer, even with me constantly taking them out to feed off to my other pets!