Gerry,
I live in Timmins (and have lived in Sudbury, New Liskeard, and Barrie - as well as having lived in Alberta), so I can give you a first hand account of what it's like living in the north (vs. the false notions of us being snowed in, or inundated with blackflies).... hahaha
I'll start with your question about insurance: Insurance rates in Ontario would be roughly double what you are paying now for the same coverage - but that is speculation at best. My suggestion would be for you to call an insurance broker in the area you would like to live, and ask for a quote. www.canada411.ca is a great place to start - Canada-wide yellow page searches.
We have pretty well the exact same amount of insects as there is in the southern portion of Ontario (outside the major centers) - I live in the city of Timmins, and there is a 2 week period in the spring where there are a noticeable amount of blackflies in town. In the bush, you'll notice the insects on days where the wind is minimal, but a little deet goes a long way in keeping you comfortable... no different at all than in the muskokas. The exception to this: If you're standing in a cedar swamp, you'll be covered in bugs (but, it's like that everywhere in Ontario).
Winters: Again, quite similar to Central Ontario - we get a little more cold temperatures, and perhaps 10% to 15% more snow fall - but you'll be far from isolated, as we have these wonderful snowplow things that facilitate us in getting out on the street... but, I would definitely recommend a snowblower (not that the snow is all that bad, I'm just getting lazier as I get older... haha)
If you're an outdoorsman, you'll be hard pressed to find a better place than Northern Ontario. I'm an avid hunter, and moderately dedicated fisherman. I can hit the old logging roads and fish a different lake every day, all summer, without hitting the same lake twice. I have found that a good set of fishing maps (most locally owned angling shops stock them) have proven to be a priceless addition to my tacle box - that way I can target specific species of fish that are prevalent in specific lakes. (I've become somewhat of a brook trout fishing addict as of late - there's no shortage of trout filled streams around my area).
The downside: we're taxed to death here in comparison to the Provinces to the west of us, and the government services that those taxes pay for leave a lot to be desired (especially in the north). Politicians do not feel compelled to send too much money back to the north, since their election/re-election does not hinge on such a small demographic (population wise).
Feel free to P.M. me if you have any other questions (as long as the questions don't involve retirement in and of itself, since I am working on the freedom 85 plan, I'll be of little help).
Shawn