Don’t have any info on LOT unfortunately. But from what you found out I would expect 3 x 3 days off meaning 9 days off minimum. The 14 days in advance mean that you get your schedule 14 days before the month starts. Be prepared to work a lot more in Europe compared to the US. Also look at the other options in case you don’t get hired by LOT. I think Ryanair and Wizzair are available. And you don’t want to fly for them coming from the US. ( hint: hard work)