Yeah, I'm not worried too much about the sailing aspect of it.
I feel
fairly confident with sail and boat control, terminology and all
that
sort of stuff. The stuff that's new to me would be trimming
sails
with winches (right?) rather than by hand, anchoring, operating
with an
engine, and probably docking (because you can't make up for your
mistakes by simply grabbing on to the dock and stopping the
boat). Oh
and navigation; when racing around the buoys on a lake there's
no need
for charts.

You're spot on. I've taken hundreds from dinghy skills to
yachting, and those are exactly the gaps. Perhaps rather than
saying 'trimming sails with winches', be more general; 'handling
ropes under strain'. That implies you know five basic knots and
can do them instinctively . . . as well as using winches. And
trimming sails will include reducing sail in rough weather.

Also: safety on board (harnesses, lifejackets, fire risks),
collision regulations (they're very different from the racing
rules) and managing crew (four on board is different, and some may
be novices, to be appropriately briefed.
--
JimB
http://www.jimbaerselman.f2s.com/
Comparing cruise areas within Greece and N Spain