I agree with everything you said. I think Carr is a solid option at 26 but he's certainly not my first choice. His footwork can improve as you said and that doesn't give me any concerns. The thing that gives me pause with Carr is his ability to stand up to pressure. He's a very prepared guy who lives and breathes football so the fact that he struggles when put under pressure really concerns me. Some guys can handle it while others can't and to me, it's not really a coach-able thing. Will he improve on that at the next level? That's the major question. Everything else about him I really like.
I'm a little surprised you feel he doesn't fit what the Browns are trying to do. Shanahan will run a variation of the west coast offense. When the QB is asked to throw the ball he'll be asked to make quick decisions and the passes will generally be shorter yardage. The system will fit well with a rhythm type QB and the best 2 rhythm QBs in this draft are Bridgewater and Carr IMO.