I purchased a C29 about 7 years ago as my first sail boat & loved it.
IMO they are a great 1st boat to learn on.
#1 I'm pretty sure the mast is 10mts from the deck
#2 I had all the thru hulls replaced when I first bought mine - see the Invoice from 7 years ago for an idea of costs
#3 I installed an electric toilet (happy wife = happy life) & later on installed a stainless holding tank under the port side V berth - I had also had a valve for bypassing it.
#4 Make sure the motor is still OK - they are getting on a bit these days but the Yanmars seem to go forever!!
There is a Compass forum with a great knowledge base
groups.google.com/forum/#!forum/compass-yacht-groupEDIT: I should add that I've never paid a marina for any work since this first time, I do everything myself these days - it's a great way to get to know your boat!!