All Mercs are natural gifted in one way or another. So higher Intel or Education doesn't necessarily mean anything.
Ansel @ 60 intelli collects 16 merch everyday. 16*4(price of merch)=62-18-10= +36 Cost of keeping him.
Peasant @ 50 intelli collects 8 merch everyday. 8*4-22-10= +0 Cost of keeping him
Loren collects 1 a day and @ 50 inteli 2. So total of around 25 merch everyday which is $100 which covers their cost of 82 and with upgrade garden and garden tools you get +2 food. So +100-82+10= +28 from day 3. Earn whatever on paid training, never train unpaid.
You need YOUR skill gte (greater than or equal to) the merc's skill to train them. Funnily enough it says that the big boy mercs will level you up if you train with them: but you can't train with them as your skill level is lower than their.
There was a feature ("bug") that if you had Ansel + Peasant + Loren in scavenger mode they'd collect 30.06 ammunition. Around 20-25 everday. This was before 814. Someone patched it. I'd get all 3 on day 1 and set them on scavenge mode.. and with every 1,2 points intel for peasent the ammo collection went up. I've never bought ammo before 814. I was 3500 or so ammo, and this worked with 30.06 only.
Kinda similar to what happened with gambling @ fury's. Very low output, randomized. Its almost like someone wants you to keep grinding - so you maybe get frustrated and cough up some doughnuts.
I don't want to seem to be hating on this game: I'm just bitching. The work grimdog has put into it is astounding.
Personal Opinion. I don't hire the issids - children in a p-game turned me off big time.