1-2 set screw helps retain spherical bearing in forged housing 3 looks like we should consider chamfering the threaded hole to sit flush, but I think its no concern for strength. You can dremel the edge of the threaded hole opening to increase surface area contact in the space pictured. Use loctite. 4. the difference here is mainly because of the difference in length of the outer tie rod joint length, MAX versus OEM Z. The actual cut length that yields maximum thread overlap and correct toe alignment will be determined by your cars choice of track width setting.
Its hard to say how long since its a flexible rubber bellow. I think its best to get one thats too long and then observe the stretch and crush to find the right length, then cut and ziptie it.