The easiest way to tell if a wall is load bearing is to check if it’s an exterior wall or if it runs perpendicular to the joists above and below it (or parallel to beams). Exterior walls are almost always load-bearing, and walls that run under beams or parallel to them are also usually load-bearing. There are exceptions to these rules, and walls that don’t fit into these categories can still be load-bearing. If you’re unsure, hire a structural engineer to look at your home to assess whether or not the wall is structural.

You may need a permit to install your window seat. Even though it's an indoor modification, some municipalities require permits for any built-ins added to homes. Check with your carpenter or, if you're DIY-ing, do some research on your city's requirements.

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. 

The cost to frame a 2,000-square-foot house can fall anywhere between $14,000 and $32,000. This price can increase or decrease depending on what type of framing you choose, the quality of the materials, the project's complexity, and whether you decide to hire a professional to do the job.