Hello!

I'm new to the forums, but I got such excellent help regarding one of my orchids that I'm returning. I just found this 5'9 fiddle leaf fig for sale at the local second hand shop for 29$, and I couldn't resist. I've just discovered this forum, and I've read about the importance of soil composition and the difference of a true repot vs just moving to a larger pot, and a lot of other things. So a bit of a lightbulb moment. Now I'm asking if you think my plan for this fig will work.

The situation:
The leaves are looking a bit dry and some are also a little yellow. The pot looks like someone bought it and never changed pot or soil at all. It looks very root bound. I can't discern any bugs or other kind of disease, as far as I can tell anyway. I have not taken it out of the pot yet, so I don't know the exact root situation.

My home at the moment unfortunately has rather small windows, and I'm not sure the light will be enough, but perhaps if I can make everything else close to perfect, it will work? We will change windows in a couple of months though, so perhaps that will make a difference.

My plan:
I'm going out to buy some ingredient for Al's 5-1-1 mix as I'm not sure I, or the plant, is ready for a gritty mix. I've found a larger ceramic pot (with draining holes, of course) for it, and will repot. But, should I trim the roots? And if I do, should I prune the plant in order for the root system to be able to care for the remaining leaves? My dream vision is a healthy plant with a thick trunk and several branches, so I'll need to trim at some point. Were/How high should I trim? Or should I wait with the trimming?

And how do I encourage the top to root?

Lots of questions, now here's some pictures