Incorrect. If the tax paid on that pension that is brought in thailand is lower than what it would be in Thailand, it may incur additional tax in Thailand.
If you can’t organise yourself to complete before arriving, you shouldn’t be travelling. The feckless that haven’t completed it should be made to get to the back of the queue again ( this is what Philippine immigration does).
Wrong. You’re assessable for tax on worldwide earnings according to this article irrespective of amount. 1 bn talks about a platform not an individual.
Not strictly true. If your hypothetical tax in country B Thailand would be higher than what you’ve already paid in country A, you are liable to pay the difference.