So when I got to the Ghoul City and the Super Mutants tried to take me to their base, I fought back and killed all of them. How do I progress in the main quest after I got the water chip and the Overseer tells me to kill the Source of the Super Mutants? They just kill me every time I get near their base with their superior weapons and health.

Also how do I join the B.o.S.? I got to the place they specified but I need a rope, of which I used on other quests. Where can I get more rope?

Thanks for the help in advance!