I have some questions about debts.

What happens, when I'm in debts?
Can I go in debts with negotiations?

The reason I ask is, that I found a great player in the squad of a friend of mine. A Q39 18yo MR/AMR/ST who is worth close to 8m, which should mean that he is a fast trainer. But a reasonable offer would be at least 10m, but I only have close to 2m atm, and I dont want to buy money with tokens, its so expensive...