No problem, it's pretty easy. The
SteamPacket company is the only passenger ferry service. They have a variable price structure according to season, with prices peaking during the TT (unsurprisingly). Cost this year for bike and rider was about £205 return for the dates we are going. It's *much* cheaper if you want to go over there off-season.
They don't set the TT ticket prices until they have an idea of demand, but you can provisionally book the tickets for a nominal fee (~£20 IIRC) and then pay the balance when they set the final price. I booked in early November, and the ticket prices were fixed at the end of January and then we had to pay the balance by the end of February. I don't know when they start accepting provisional bookings, but give them a ring and they will tell you.
I simply rang them up, asked to book 6 bikes and an extra foot passenger (pillion on one bike) and paid the provisional booking fee over the phone on a card. You can chose the sailing times and port (Liverpool or Heysham) from the website. They sent a booking confirmation through within a couple of days, and then sent an invoice for the balance in January which I paid over the phone again. That's pretty much it, you don't get any proper tickets as such, just a booking code that you need to have when you board the ferry.
In terms of accommodation we are staying with some friends of one of our party, but there is plenty of camping and guest houses/hotel accommodation as long as you book early. I've heard lots of good things about homestay as well, plenty of friendly people on the island happy to provide accomodation to bikers during the TT. The
IOM TT Forum has a section for accommodation where homestays are advertised.