Joe, with a kayak your launch possibilities are endless. Many accomodations have waterfront access, so you can start there. The city docks/launch are very busy with powerboats, but are another possibilty.
My first visit to CK was last May. I started my research at the Cedar Key Chamber of Commerce website, and found links from there. You won't believe the number of keys/islands within paddling range of CK. I took my flats boat and still had to worry about tides, but with a kayak, you'll be fine.
When I was there in May, spanish mackeral, redfish, trout and ling were being caught inshore. I would think March would be similar.
The best thing about CK: my Nextel (and nobody else's) would work. First time in years I spent a week without that 'beep-beep'.