I don't think plantation shutters would help. Hang roman shades at the same height such that the bottom hides the top molding of the windows and then no one will know they're not the same height. Make sure the shades are blackout lined so there's no light coming through to expose the difference.

Have someone come out and give you a quote on making that window larger.

The fireplace looks totally out of place - get rid of it.

I agree with kandrewspa.

IMO wait until you decide about the FP . Why is the TV sitting there ? I need a bit more info and for sure if this is a home or an apartment ?

You should play with drapes and blinds to get some balance with windows. I would dress windows the same way.