Re: Indoor practice
I think you should try every cast and every rig that you can imagine.
When I started, I practiced in my company's warehouse and it helped me a lot.
I don't know if you have a pillar, a column or a vertical obstruction there, but I used to stand about 20ft away in front of one and practiced my cast.
The purpose is to know if your backcast is straight or not. A curving backcast will hit that pillar/column. My warehouse also filled with crates, I used them to know if dropped my backcast or not to practice my timing.
Another thing, use your old line and use heavier and more wind resistant practice fly. This is to compensate the perfect no windy condition.
Good luck young Jedi.
Bruce White "Fish are friends, not food"