Is there a reason why you are not checking backs through from BOS? I would do it that way, and in that case 13 hours is fine. On the return 1:50 is OK for through bag check, with a slim chance that they might not make it, but I guess you're going home, so no big deal. Again you should be able to get both boarding cards at your starting point.

When it comes to showers it depends very much what class you are travelling in...