It seems crazy to me that some people find roundabouts so hard. I've always found them pretty intuitive but I'm definitely biased, when I was learning to drive there were about 8 roundabouts of various sizes near my house and I'd invariably have to take at least 3 at the start of any journey.

It's probably just because we're so used to them here but pretty much everyone seems to know how they work. Off the top of my head the only exception is one badly designed roundabout where you're meant to stay in the outer lane unless you're taking one exit that's practically a u-turn, people always take the inner lane (like you'd normally do) and have to change last second.

Not sure there. In the UK, the inside lane is generally (based on the signs on the road) for those who are going to the at least one exit further. Once your exit is the next exit, you'll change lane to make the exit. You can't simply making the exit from the inside lane unless there's sign on the road telling you to do so.

If you enter to the inside lane you exit to the inside lane. Given how roundabouts are designed in Ontario, this ensures that traffic entering from the range direction never crosses: Right lane either exits right or goes straight (first or second exit), inside lane goes straight or left (second or third exit), just like at an intersection without dedicated turn lanes.

That's not really how roundabouts work. In 2 lane roundabouts the outside lanes have mandatory exits where the inside lane can exit as well (since the outside lane cannot continue, there is no accident risk). In some roundabouts the inside lane becomes the outside lane at these junctures. At others the incoming outside lane takes over as the outside lane.

In any case, when entering a roundabout there is signage which tell you which lane can do what, so you only have to enter the roundabout in a lane that goes where you want.

This is no different than any other intersection, you have to be in a lane that goes where you want and you shouldn't change lanes in an intersection. It's illegal in many provinces and counterindicated in others.

https://www.theglobeandmail.com/drive/mobility/article-is-it-illegal-to-change-lanes-in-the-middle-of-an-intersection/

Most roundabouts in Ontario are two lane roundabout. I have yet come across a three lane or four lane roundabout

My general consensus for two lane roundabouts is treat the inside of the roundabout as you would a regular signaled intersection, in that you dont change lanes inside the intersection.

If you came up to the intersection on the right you exit straight, or turn right. You can't change your mind inside the intersection and turn left from the right lane. (Though this does not seem to stop a few motorists I have seen).

Alternative view of roundabouts (same principal), treat them like a continuous roadway. If you are in the right lane you dont suddenly turn fully left. Similarly if you are in the far left you dont suddenly turn fully right cutting everyone behind you off.

To add, if you did enter the roundabout incorrectly and ended up going in another direction then you originally desired, its generally best to continue through and course correct on the next roundabout or car park/parking lot.