Bill:
Sorry I haven't replied sooner. My Sister-In-Law had twins and my wife
is going nuts about it. Doing lots of travelling to see them since the
holidays.
As for how long a Fluorocarbon leader. Use about 5 or 6 feet. Tie it on
your mainline using a double Uni-Knot or a Surgeons Knot. A double
blood also works. If you tie things right you won't be bothered by the
little knot. If you make the leader to long the knot ends up on your
spool and that can sometimes create problems.
Take Care and Give this a try.