Are you wanting to buy something off the shelf or is he interested in building one?Off the shelf and portability isn't an issue
Home computers are usually better if you don't care about portability.
Sounds like it might be best for you to opt for the surface pro 4.My sister said she suggested the surface Pro but a friend said not to bother. To be honest her friend probably doesn't know what he's talking about. What would you suggest for the drawing pad?