I am renovating a former three-season porch at my home. Among other things, I planned to remove the drop ceiling tiles (and strapping) and put up a tongue and groove ceiling. When I removed the ceiling, I saw two things that troubled me. First, I saw joists that were horizontal on which the strapping had been secured. Can I remove those joists without compromising the integrity of the room? Second, I saw that the rafters on the sloped roof were of different heights, such that it would be impossible to put up sheet rock and tongue and groove paneling. How should I handle this problem? Should I put up additional joists that match the height of the tallest joist? Any advice would be appreciated on either question.