1) I kept my OEM UCA's and I agree with the others about their benefits but I don't see them as a necessity.
2) Negative
3) This lift was designed by ARB to keep the CV angle at a minimum so you wouldn't blow through boots or cause excessive damage.
4) depends on which springs you use, I have the mediums in the rear so it sits higher but I also have a custom security/cargo management system and carry extra weight due to the gear I carry on a daily basis. When I do a front bumper and winch I will get the stiffer springs. I never measured before/after but I would say at least 2.75". Pics are on here if you search

just my $.02 and I hope this helps