1. The Canadian health care system is rife with nepotism so unfortunately you're right. The Royal College is an opaque and frustrating organisation. I hear Americans complaining about the ABIM, they have no idea what we have to deal with up here.
2. Yes it's the linked Toronto review course not the Toronto notes.
3. Note, the review course has a small question bank (and an oral examen practice section) that is pretty good.
4. As for guidelines, no there's no source. It's a mystery always which guidelines they prefer. I'd recommend reviewing Canadian guidelines for high yield topics: HTN, AF, HF, ... American guidelines are used when the Canadian ones are outdated or non-existant. The Review course gives a more or less complete overview of these guidelines as well tbh.
5. I don't think uWorld is completely useless. On its own maybe not enough to pass but useful. Basic IM topics like heart murmurs, JVP, MEN, vasculitis, ... all come up and those aren't guideline based anyways. I think a refresher on high yield topics would be good. Don't waste your time though on primary care stuff such as OB/GYN and psych which are not tested on the Canadian exam.
6. The internist who runs the review course is really nice and approachable. I'm sure you're not the first person to go through it like this, I would suggest after you sign up to reach out to her and ask her advice.
I don't want to discourage you at all. I think it might be a bit of a challenge but at the end of the day, you're a board certified internist in the US, this is an IM exam not a surgery exam. Do with that you have; immerse yourself with the Toronto Review course, review some guidelines, and review basic IM w/uWorld and it will likely work out just fine. Because of the opaqueness of it all, I'm sorry I wish I reassure you more but I can't.