Katang--
No rostering, it is a bidding system based on seniority. The lines are built and put out and we bid our choices (again, awarded based on seniority). Reserve lines have 6 consecutive days off in a row every month. Some of us are commuting to the States during those days off, and it isn't easy, but it is doable. Europe should be a piece of cake, and you should get 5 full days at home (as opposed to 2 or 3 to North America).
Most of the lines have a block of days off as well. And, you can trade trips with the other pilots to try and improve them some. The rumor is that we will get a line every third month, but I haven't heard anything official on that, so who knows (it may be truth or it may be wild speculation)... As Sabre comes on-line, trip trading will get easier (you'll be able to trade with open time and completely rearrange your schedule without dealing with a live person). When will that happen? Again, who knows. But if it does, they are saying no more straight-reserve lines -- it will be some trips mixed with reserve days (mixed lines). Good for us at the bottom of the list, at least we'll get some good Europe flying...
Total days off per month varies. Again, on reserve, only promised 6 days (consecutive) off. Throw in a 24 in 7 break, and I average 9 days off on reserve per month (however, I only flew 6-8 days a month on average on reserve, the rest were standby -- hopefully that changes as we get busier over the summer). The lines seem to average 11-12 days off per month, with one big block of days off and then 1-2 days off scattered throughout the month. Again, the caveat here is that is until now. With the accelerated parking of the MD-90's, I was told we are going to get BUSY for the rest of the year starting in June. So, we could end up working all the time. As someone said above, it is in a state of flux right now and everything changes by the day.
Also, on another note, listen to metro301 when he says that it gets better once you're on the line... I have to admit he knows what he's talking about.
Things are a little unpredictable right now, but they are definitely getting better...