I would think he means that Dunlop would give him free picks or GHS would give him free strings, in exchange for being an official Dunlop/GHS user.

I would find it hard to imagine that they'd give you cold hard cash upfront just for wearing a t-shirt or something.

I don't know anything about it, either, but one risk I could think of would be if you locked yourself into a contract. That's a mistake young people make a lot, since 5 years or whatever doesn't seem that long. You never know when a better offer is in the pipes.