obvious committment to doing a good job on your home. This is a situation where I would highly recommend your engaging the services of an architect familiar with the codes and building methods applicable to what you are trying to do. You as well can be apprised of other possibilities you might not have thought of. I would contact some of the general contractors in your area and ask for a referral to whom they go to for specialty framing design. You can engage the architect for anything from just an assessment of what you have posted here all the way up to a full set of building prints. Luck, Kizmet.