I just purchased a 26" clipper sailboat. It is going to require a lot of
fixingup. The wood inside the fiberglass hull is going to need replacing.
I
do not know how to attach wood to a fiberglass hull, what kind of wood to
use, how to sucessfully remove the interior without damaging the hull. Any
help would be helpful.

A few thoughts, have you checked that the cost of fixing it up makes
financial sense? If it needs that great a level of repair it may be very
expensive.

For FRP I would use an epoxy resin for wood-hull joins. I suggest you get
hold of a book dealing with boat repairs in the area you're working in (FRP)
of the serious rebuild variety. www.amazon.com.

However, before parting with any more money, and given that you come across
as someone who has very limited idea of what to do, ask if you have the
necessary skills to do the work required to a sufficiently high standard (it
could be your life at stake). I would seriously consider cutting your
losses and getting hold of a boat in better condition.

remember that this advice is worth precisely what you paid for it.

Al