Hello Rudolf
The bidding system doesn't really work. In theory there are five bid groups which rotate so seniortiy isn't really a factor. In practice there aren't enough pilots and the company likes it that way so the roster computer can't do its job. Hence there appear to be lots of last minute insertions after roster build as the computer desperately tries to fill flights. A junior (or senior) pilot can expect very little control over their schecule and swapping is very difficult because of many company "rules" that aren't written down anywhere. Lack of satisfaction with rosters is a major reason for people leaving. Bidding closes on 5th and rosters are usually produced between 16th and 18th of the month before but it can be as late as the 23rd. On the plus side, rosters are generally fairly stable- they are usually so busy it is difficult for the company to mess with them after publication.
You will get 35 days of reserve every 10 months regardless of time in the company. Some reserve months are very busy, some not at all. You don't find out what you are doing until 1800 the day before and don't know when your days off will be until the night before either.
Hope that helps. Nobody joins Emirates for the quiality of the rosters!