Can he plan a trip as well? E.g. I know where I want to go (from reports I read on the internet) and may have an address or directions, but of course no map and no idea which is the best way to go and how long it will take.

Prices for long, multi-day guided tours include the customer paying the cost of fuel, meals, and accommodations (where necessary), plus a daily stipend (negotiable within reason, in advance). To save you baht ... on multi-day trips he is quite happy to book into a (cheap!) Thai style hotel while you, his customer, lazes about in luxury at The Four Seasons Resort and Spa.
Is everyone here afraid of numbers? As I never used similar services, I am curious what the daily stipend would be for let's say a five-day tour (in addition to which one would have to pay fuel, meals, accommodation).