kmp1 - rostering is done by the computer system. we don´t have any seniority in the UK base so there is no bidding for rosters only for annual leave and that´s done on a ´bingo´system. Once you get your roster it´s up to you to change it by trying to swap with another crew member. You can´t really drop a trip unless you´re picking up another trip starting earlier. You can ask crewing to get you a trip on an earlier day if there is one to pick up, then you can drop your trip. It´s a first come first served thing with picking up trips in "open time".
Jump seat or crew seats are only available on request when you are travelling on staff travel by asking for permission first. I think jumpseats are available to flying crew only and crew rest seats to crew and families by asking permission from the crew working that flight.