I would have a larger school of tetras than just ten. In that size tank, especially alongside discus, I school of 30+ would look amazing. I prefer cardinals, but rummynose, serpae, and others can all look great.
I have seen people with 11 healthy adult discus in a 55, but honestly in that size tank, especially with other fish, I would aim for around six. It really depends on the maintenance you want to do. Any discus tank should get at least 50% water changes at least weekly. If you can keep the nitrate concentration under 10ppm and want to add more you should be able to.
What else are you wanting in the tank? You didn't mention any maintenance fish. I would have bristlenose plecos for algae control and sterbai cories for cleanup.
Are you going to plant the tank?