For the first part of your question you'd have to refer to your contract for the information. There's a pay scale calculator from APC which you can plug in your hourly rate and minimum hours per month and get a rough estimate. As for the second part - yes. Holding a line is relevant to seniority in domicille or base. Some pilots sat on reserve for only a few months before being able to hold a line. Others had to spend a year or more. It just depends on what is going on at your company at the time.