Can someone please give a technical explanation of how they find (how this similarity search works) private key after someone already finds the private key and starts a transaction? I know mining means finding a part of private key and these private keys are in a narrow window. But there are too many pools, so I would expect to 1 or 2 approvals "quickly". Even if my transaction got let say 1 approval are they allowed to cancel the transaction when they have private key?
Is it a naive approach to create a bot to make ~60 transactions 0.1 BTC each?
This was discussed to death dozens of times, why don't you read the last pages of the thread?
Once the private key is found it is inevitable to have to make its public key, well... public when you create the transaction, so that the signature can be verified. It doesn't matter if you create 1 output or 100 outputs. Since the public key gets, well... public, everyone will know it. Knowing the public key of a "small" private key (< 100 bits, less or more depending on current technology) allows to find the corresponding private key in anywhere between less than a second and 10 minutes, before your original transaction gets confirmed in a mined block. Knowing the private key allows for creating a new valid (signed via the private key) overriding transaction, with a higher fee, which replaces your transaction, irrelevant of how it looked like or of its content, flags, etc.