We use mostly automated processes, with manual intervention only for rare edge cases. One thing that's surprised us is just how many (i.e., non-rare) edge cases there are when you take into account shipping exceptions, order constraints, etc. We believe we are on solid footing both legally and technically, and this has been supported by three years of reliable operation.
Unfortunately we're unable to use most affiliate programs. At the same time, we're mostly interested in building a framework that easily scales across to all merchants.