You don't have to spend $50 on the clear lenses however if you do you'll get more color flicker at the cutoff.
They will fit in the stock housings, I emailed retrofitsource.com and they said they will mount with no cutting of the housing. However I'd mount them with nuts, bolts, and lock washers.
Pull the pgm mall fuse and follow the steps to disable the headlights flashing when you lock the car from your key fob. The DRL can be disabled by pulling the fuse!