Insurance, contents insurance, has been a pain; no idea why, but sorted now. We have building insurance, but we have an unusual freehold/ leasehold situation so I can't tell you much about the cost/detail. I don't think it's been hard. No problem with mortgages, but I guess the condition would have to be good, like any other house. If it's been really neglected the wood could conceivably be rotten. We paint the whole building every 10 years.
We have triple glazing and also a heat exchange system, and underfloor heating. I know people who regret not getting the heat exchange system as they suffer from condensation. Ours was also well built; I think they can suffer from lack of attention to detail with regard to proper watertightness etc, but ours is solid, gorgeous, warm, and delightfully slightly creaky in high winds (but totally supposed to be).
No more spiders than anywhere else, but we are in the countryside.
I'd always lived in old brick houses too, and it's been a revelation. You shut the windows and no wind/ cold comes in, even in winter!
The wood is wonderful. It feels like a living thing.