Yes, ceiling joists are typically load-bearing. However, their primary function is to support the weight of the ceiling and loads applied to it, like lighting fixtures and ceiling fans. They can also help support the roof, especially if they’re part of truss systems. Remember, the load-bearing capacity of ceiling joists depends on the material, size, and space between them. 

Converting a carport into a garage can vary in difficulty depending on its configuration, the condition of the foundation or slab, and its location relative to the house. The process has a lot in common with a home addition, but you can often skip non-essential finishes like fine flooring, trim work, or even drywall and HVAC. The conversion requires experience with drywall, insulation, and other building materials to ensure it’s done safely and correctly. While it might be possible for a DIYer with the proper tools and skills to do the work, it is a complicated and potentially dangerous job. If you’re new to basic construction, it's best to leave this project to the professionals.

Bump-out additions can extend anywhere from 2 to 15 feet from an existing room. The right size will depend on how you plan to use the new space. For a cantilever bump-out, which doesn't require additional foundation support, the limit is typically 24 inches (2 feet). If a footing and foundation are part of the project, a bump-out can be much larger, even encompassing a whole room. It's also important to remember that many residential properties have limits on the total house size relative to the lot size.

Yes, walls on the top floor can be load-bearing if stacked on the floor’s foundation.