Well a good thing I thought Pathfinder allowed was to craft poison using the alchemy checks. I mean, it stops the ridiculous idea of having more skills than you could afford to be good at it. One of my problems with 3.5 was with those skills...
About those DCs... well on your D&D wiki link there are most of the DCs on the second column, no?
And I thinks it's
pretty much up to you. You could always give him synergy bonuses if he has those 2 craft skills, or you could agree to let him do stuff with alchemy, but I must point out that on the Wiki you sent they categorize poison as "Alchemical" so....