I'm a character attendant now, so I'll do my best to answer your questions. I never intereviewed to be an attendant, so I can't help you there but I can help with everything else hopefully. Sorry if everything below is kind of scattered, I'm just writing as things come to me.
An average day for an attendant really isn't too tough, depending on who you are working with of course. You're biggest responsibility all day,every day is the safety of the characters and maintaining character integrity. As much as we are trained to be all about the guests, answering millions of questions and talking to them while they are in line, you need to care more about the characters. Basically, keep one eye glued on the characters and the other eye glued on guests while interacting with both the characters and guests.
If you are standing just watching your character all day, you are going to have a boring day. Talk to guests, talk to the little kids that are scared of the characters. Even more so though, interact with your characters. If you're bored up there, chances are they are too. Have fun with them, play games, make stupid comments and laugh with them. It all makes the day go by so much faster.
You're biggest responsibilities every day will be to make sure the characters are out on set on time and that they are taken off on time. That is one of the biggest points I can not emphasize enough. Wear a watch everyday, you need it. You live by your watch. Depending on where you are and who you are with each day, you may be doing 14 sets each day.
Probably the toughest part of your day, every day, will be to turn people away when you're line is closed. No matter how cute the kids are, how nice the parents are, you can't let them in once you have closed the line. If you let them in, then you have to let the next family in that sees you too. You also have to be prepared to deal with begging, angry guests or guests that will try to push their kids into line after it's been closed. It's all about sticking your ground, and being as nice as humanly possible no matter how irate a guest may be. Don't worry though, really, majority of guests are quite nice and understanding. You can never let an angry guest ruin your day.
Working with the characters is a blast. Have fun with them. Talk to as many guests as you can (while keeping at least one eye on your character at all times). It's always a blast.