Hi,
First thing i have to told you that you can not travel around Halong by cruise in 1 day, you need 2 days at least with 1 night in cruise. Halong have many wonderful cruise for your choice such as Victoria cruise, Halong Charming cruise, Palace cruise and so on. You can visit Tripadvisor to find suitable tour and visit Halong-Bay-Tours to book tour as well. The last trip in Halong i also booked Charming cruise in there with good services and resonable price for 2 nights. About transfer, from Hanoi to Halong, you can catch bus (4-5hrs) or contact with tour agency who will have pick up you at your hotel.
Happy travels!