Not really sure what you want advice on.
That aquarium is very cloudy. Is it always like that? What filter do you have? Do you know your water parameters? Have you tried anything to get the water clear?
The tetras are glofish, which are genetically modified to give them that fluorescence. Glofish call that type a longfin tetra, but the actual species is a black skirt tetra. The colour varient is Moonlight Pink is you say. Good bit of investigation on your part.
Tetras are social fish and should be kept in groups of their own species. When kept in small numbers They will be stressed and stress causes unpredictable behaviour. They might get aggressive, or hide away, not feed, etc. Or they might just get on with things and make the best of a poor situation. But, stress is never a good thing, and will cause health issues over time. So, I would look to add more of this type of tetra. Either black skirt tetras or the GM glofish long finned tetras. A 75g tank can hold a lot of fish, but look for a group of at least 10 tetras.
75 gallon is on the minimum end of suitable size for a 13" pleco. Depending on the species, it could get to 24" and need double that.
If you want to add driftwood be prepared for a couple of things.
It will float. Weigh the driftwood down until it waterlogged and stays down on its own. This might take months.
It will leach tannins and make the water tea like. If you don't like the appearance water changes will remove the tannins, and after a while, maybe a few months, the tannins will all leach out. Activated carbon added into the filtration will absorb the tannins, and again it will eventually stop leaching out.
Plants. Get some easy to keep plants to start with like java fern and anubias. You can simply tie these plants to a piece of rock or your driftwood. They don't need planting in the substrate, and don't need a lot of light or nutrients. They are as bullet proof as they come. After that, look at some other easy plants like amazon swords, java moss and cryptocoryne.
Clean up fish? Have a look at corys or loaches. Again 75g is a fairly big aquarium and you have plenty of scope for fish. Maybe look for a bigger cory species. Or a medium sized loach like a yoyo loach.
