Loft will create the simplest surface that goes through your curves. No need to add more constraints with rails, in this case it would probably add complexity and imperfections if your curves are not perfect. Have confidence in the math shaping the surfaces!
It’s good practice to use the simplest tool possible to get the job done and loft is the simplest while NetworkSrf is the most complex. BlendSrf, Sweep1, Sweep2 are in between. NetworkSrf has its uses but a lot less often than the others.
Trimming is not something to avoid. It’s part of of our toolset and the best way (sometimes the only way) to build some shapes. You have to understand what are the uses, the limitations, best practices.
So, answer 1; because the math at work to loft a surface between your curves will produce a smooth edge between the curves endpoints. Answer 2; try it, but in this case I think you won’t need it. Answer 3: it’s easy and fast to try it yourself. You can find a video of someone using Loft on a bunch of curves but you won’t know why your results are different.