You will most likely be working for a state or province. There are several jobs listed if you google "jobs in historic preservation". The state of Georgia is looking for a manager for their Jeckyl Island at $60,000 to $68,000 a year. A degree in HP and experience are required. Also check out the 'ncpe.us' web site for a list of schools that offer a one year masters degree.

James, are you looking to work in Canada? If so, your best bet is to try and wedge yourself into the federal gov's offices under PWGSC or some other municipal department that deals with building permits... Most I've seen advertise, besides requiring a good knowledge of both languages, seek a licensed architect at the bare minimum.

If you want to chase the conversation path, complete an undergraduate degree in one of the few universities that offer that path in their BAS degrees (Carleton and Université de Montréal I believe) then take their 2 year M.arch.

As for your last question, I don't know what enviro-design teaches differently than most 1st and 2nd year tech classes at Canadian arch schools. You'll be at a disadvantage because you're competing for entry-level jobs with more rounded students. Also, unpaid internship... what the bloody deuce? I hope that was not in Canada because shit like that is not legal.

Not to be confrontational but the jobs I researched here in the states seek experience plus a degree in Historical Preservation. None specifically seek an architectural degree as a prerequisite. It would be something the OP needs to determine by talking with people working in the field before expending a lot of time and money.

You don't have to go down the license route to be a conservationist.  It really depends what sort of work you want to do.  Have you seen http://www.arct.cam.ac.uk/courses/mst-building-history-1 ?

Thank you all for your advice, I really appreciate it.