I wouldn't keep Clown Loaches with Discus, they move pretty quick and would disturb the Discus at the night. Cardinal Tetras would be fine, as would some any Corydoras that could handle the higher temps. Your Rams could go in the tank also.
If your sig is correct your 35l tank is not suitable for some of the fish in it, I will assume you know that already by reading posts on here. Also you should keep your Loaches, Tetras and Danios in groups. I would sort out this tank before even considering Discus, you will also need to research into Discus and the water requirements they will require if you are to be successful. You'll need to decide if you want to dedicate the cost/time into them.