Hello !
Be sure to use the latest downloadable build of MM3, because some bugs have been fixed that may help you. For example, you should be able to set any kind of aspect ratio/camera lens now (we have no limitation at all).
About your maya export issue, did you check that the frame rate is the same in MM3 and maya, and that your first frame index is the same one as matchmover. In some cases, users have to change that to make the export working fine.