Greg,
He has a 400D. I would avoid going past ISO-800 for relatively noise-free images. If you're not doing time lapse, enable in camera noise reduction and high ISO noise reduction.
As for lens, you'd want something in the 10-22 range to give the equivalent field of view as the full frame cameras. Canon has a 10-22, and Tokina makes a good 11-16. Being a Canon zealot, I avoid third party lenses myself, but, that's just my personal preference.
Also, if shooting RAW, why would you set a picture style? Leave it at standard and set it in post to your liking.
H