Hmmm, this struck me: this company almost lost a major client because they let an unsupervised (probationary?) employee handle a major account? And what they learned from that lesson was that they should hire someone on a trial basis and pay them even less money to do that work??

It sounds like you are very good at what you do, but it is a very strange thing (imo) for a company to place this much power in the hands of a probationary employee who has never been in the business before. To me this signals that they either have a problem paying people or they have trouble making good decisions. It sounds like you are making a lot of outside contacts in your position, which will be great for finding a new job.

This sounds like the kind of company that would give you a raise to 32k a year, 3 days vacation, and switch you to a salaried position (no overtime).

Trust your gut with these people. From what you've said, you have every reason to be wary. You have a right to ask for clear information about your situation and to ask for it in writing.