Lots of question, lots of answers, lots for you to think over. For one, how likely are you to buy the 2.35 lens? If not now, when? If you aren't going to do it soon, I would probably buy a less expensive 16.9 screen that you can sell later when you want to step up to Cinescope. If you are prone to do it soon, then get the wide screen now.
Keep in mind that when you change from 2.35 back to 16.9 you have to move the lens out of the way and you will have left over screen on the sides. You could mask with drapes, etc if you had a fixed screen, but not so easy with a motorized one. It can be done, just not as easily.
So, it's really a matter of preference, money you want to spend now or later, and how much you want to be inconvenienced each time you change aspects. 2.35 is most inpressive, though!
Nice choice of pj!
Welcome to the forum!