Advice needed for Hanoi - Ha Long - Cat Ba - Ninh Binh - Hanoi loop!

Hi all,

Am at the Phong Nha Farmstay at the moment (have loved every second of the 3 days here btw) trying to figure our plans for the next week or so. The Ha Long Bay part is driving me nuts in spite of massive amounts of research. Any tips and ideas would be very much appreciated.

So far this is what I'm intending to do:

Sat: Full day Hanoi
Sun: Leave Hanoi for day time junk cruise tour of Halong Bay dropping us off at Cat Ba island for first night
Mon: kayaking Lan Ha Bay (possibly as part of a 2d 1n kayaking camping tour)
Tue: either finish tour or, if not going for tour, hiking/biking Cat Ba. Leave for Ninh Binh in afternoon/evening
Wed: whole day for ninh Binh area (tam coc etc)
Thu: more ninh binh area, evening bus back to Hanoi
Fri: fly to Vientiane late afternoon, spend morning sightseeing or hungover

Any recommendations for day cruises that pick you up in Hanoi, sail through Ha Long Bay and drop you off at Cat Ba one way? Is this available?
Is Lan Ha Bay easily explored independently in kayaks?

All comments appreciated :-)

Anne