You can find some info on Blighttown Skip here: https://wiki.speedsouls.com/darksouls:Blighttown_Skip

There are different setups for aiming and positioning depending on the route.

It would be better for you to ask in #ds1-help in the discord when you have specific questions/problems. It's linked in the game page.

Correct.

Good luck with that, that's a known extremely hard glitch to reproduce.