We love the Island! Never caught a ferry there though, so no idea on costs. There is so much to do, Cheshire mentioned lots of them. The main town Cowes has lots of shops and cafes too. The fish and chips at San Remo are awesome . You can do lots of trips to the popular surf beaches too - Cape Woolamai and Smiths beach are great surf beaches, but there are plenty of others.

For accomodation - do you want to stay in a hotel or holiday park? There are heaps around. I'd try and choose one in Cowes, close to the shops and beach so you don't always have to drive somewhere