Assuming you got the kit that comes with the coilovers and the a-arms and such? If so you don't need anything else. IMO it's the best budget K on the market. Alot of people badmouth UPR but I've never had any issues they couldn't resolve to my satisfaction.
If you don't lower more than an inch you really don't need one. If you got the kit for drag racing/street use I wouldn't really lower it that much any way.
The bumpsteer kit is just an extended, adjustable tie rod end. It allows the front end more adjustment for alignment. I know when i had my k-member kit put in they couldnt get it aligned properly without it...