Hi! I did merchandise in fantasyland in the fall of 2009

I'll try answering your questions for you. The best way to use the bus system I would say is take the bus just earlier than the one you would take to get you to work right on time. Disney is really strict about being to work on time. One minute late and you have half a point. Sometimes there are unforeseeable things that happen, like some of my friends were trying to get to work and their bus had a small fire, so they had to wait for another bus to come and get them from the side of the road. But that doesn't normally happen. Also it's good to be at the busstop around 15 minutes before the bus should be there, because sometimes the bus will come and leave a few minutes early.
You can pick up a shift in any other merchandise area. But you'll be scheduled in the area you were trained in. Sometimes youll be deployed to other areas, I was deployed to Tomorrowland merchandise for a week. Its fun to work in the other areas because they don't all operate exactly the same in the way they do things.
Unfortunately you can't pick up shifts in attractions or character attendant, because you need training for those, and again, unfortunately, as a cp you can't be asked to be trained in those roles either. You can pick up PAC(parade audience control) shifts, which are under attractions. I love PAC, because I extended my program into that role...I do wish the people who picked up those shifts had training though, as we went through specific training for it. But oh well

Pirates league is still open, but it's very hard to get into. On of the awesome members on this board Berlioz70 has mentioned how competitive it is. Was it something you mentioned that you were interested in during your interview?
Anyways, merchandise is an awesome role and there's loads you can do to make magic for the guests!