Ok so here we go
My retrofit is the Morimoto Mini Projectors (http://www.theretrofitsource.com/pro...au9f0spgqfsral
I didnt do them myself, but I know that these just fit right in to the housing and I think they twist in, its suppose to be really easy.
Okay so as far as the relay goes, you dont need one. With my HIDs I used capacitors right before the ballast, you can buy them on ebay relatively cheap, I have not had any problems with them. You could also do the resistor trick but then you have to splice into your factory wiring.
And as far as the light output, it is much better than stock housings with HIDs, but it takes a little while to get used to the cut-off. The bi-xenon kit that i linked pulls up the cutoff when your turn the brights on. This is what the cutoff looks like