Well that is a possibility? But unless you provide some evidence, all it a pure speculation.


Same, he/they can be a single person, a group of people, we DON'T KNOW.


Many Replacements can be done until almost 100% of the balance become in a Fee for the miner.

But this depends of how many time a miner takes to mine that specific block, it can be 1 second from your TX or some hours from IT, that is something that we don't control.