I'm entertaining the notion of promoting a new skin care merchant and I'd like input from you retail types!

Those of you who know PW know that we run a lot in the financial services space, but in our effort to diversify we're expanding. I was approached recently by a skin care merchant (brand new, not out yet, nothing cheesy) with FANTASTIC clinical studies and they'd like help in building their affiliate program. To anyone with this traffic - what do you already know that I should keep in mind?

1. Do affiliates prefer one commission for one sale or residuals for the monthly renewals? (It will most likely be sold in 30 day supplies).
2. Do you find marketing clinical/science/statistics to be more effective than hip/trendy/cool?
3. Shopping cart model or free trial (shipping only) with automatic monthly renewals?

Your input is appreciated.

(Mods, feel free to move this elsewhere - wasn't sure if this was the correct forum.)