Second question: You should mention some well-known technical products related to your parts, not all of them. You can simply mention the whole well-known technical product in the background.
The third question: no, you only need to describe your parts completely and clearly, and the parts can solve the technical problems you want to solve, such as wings. You can invent an improved wing, which can reduce air resistance.
The fourth question: sovereignty should write the most important part of your invention, not the whole. For example, in the past, the cross section of the wing was rectangular, and your invention was elliptical wing. You only wrote sovereignty as elliptical wing. As for the length and thickness of wings, it is limited to the right. If you want to write general aircraft in the claim, you can add a sentence in the final claim: aircraft using the wing described in claim 1.