Given the nature of your Q's, I'd suggest you try to locate a Niagra owner's group on the web. Failing that, you might look for some BB's that would be likely to have Hinterholler owners - e.g. there was a very nice Canadian BB several years ago that focused on sailing and many of the posters were very familiar with/owned Canadian boats. And finally, it may not be too difficult to find who were some of the Hinterholler dealers in your region of the country. There may well be someone at one of those dealerships who has a depository of useful info you could mine with a phone
Congrats on the purchase
and good luck on shucking all 'the stuff'.