Well yea...you can 'toss' any fish and any plant in there - BUT
.....Chances are you'll be back here posting real quick something along the lines of "plants turning yellow, fish dieing, fish has hole etc etc"
To avoid these headaches, easiest thing is: Test your water for pH & KH, whatever the result, there'll be a nice range of fish you can house in this water - See what you like from them, that then won't be followed by upset posts
Same on the plants, some need more light (> more nutrition) other don't.
You can house shrimp either in community tanks or (like me) in sperated small tanks. Their behavior is too awesome to watch and too funny at times. Ideally for them to stand out best way possible, you want a heavily planted tank with dark substrate for them to live in. Apart from my profile, here's more shrimpy pic's http://www.tropicalfishkeeping.com/f...ictures-34455/
Like I said before, KH & Ph unless you already have your eyes set on ONE specific fish - Whatever the result will be you'll have plenty fish options. For NO2, NO3, Ammonia - At first while cycling you will see these numbers rise & fall, thereafter the goal is to keep them 0 - If that's not the case, something is wrong in the tank (often due to too lil water exchanges)
If you want Discus again, go for it! Maybe 2 of them, a nice school of Tetra's and a school of 10-20 Cory on the bottom - Provided you have soft acidic water to support this idea