It might have been a better idea to find accommodation before you booked flights, availability will very limited and prices will be shocking! The busiest week of the whole year is the week of the "Battle of Flowers" festival, 14th Aug, usually every bed in Jersey is taken. You can book accommodation centrally on the Jersey Tourism
St. Aubin is a small village and has a number of small guest houses, centred round a picturesque harbour with good restaurants and pubs. It's only 3 miles from the capital St. Helier on a good bus route so easy to get around. Can also recommend the railway walk, a 3 mile footpath that leads from St. Aubin up to the well known Corbiere Lighthouse. I might be biased as I was dragged up in St. Aubin but if this sounds good to you I will list some guesthouses in this area when I get a chance.
Rib charter is available here