I believe it's Monday nights if I recall correctly. We were there in July, 2009. Cost was around $27 for adults (10&up) and $13 for kids (3-9). It was really cute, the kids enjoyed it very much.
I don't think you have to made an ADR much before the week before you go. We did it last June and everyone had a great time. We were 8 adults and 3 children.
We went last july. DD seeing Donald, but unfortunately Mickey was not there. The food is the same mediocre BBQ fare that Disney serves everywhere (WCC, MBYBBQ, etc.) Ithink we had the same meal 3 times that week between WDW and VB. Shutter's regular menu is much better, but the kids do enjoy pirate night.
It is on Monday night. Very average food but it is all you can eat. The kids loved interacting with Pirate Donald and Pirate Goofy. If you have kids do it. If you don't skip it.