regarding I.P. addresses, if you are aware if VPN then it will be no problem, creating new bitcoin wallet address and use it once. In our country there are 3rd party apps that lets you exchange your bitcoin with out you submitting KYC protocols, as long as it is in the minimum withdrawals of a thousand dollars.
That's right, I think some exchanges will still comply with the regulations regarding KYC so if he is asked by the investigators I think he is obliged to notify. If not, then I think the exchange will be in big trouble. So maybe the confidentiality is maintained, but if there are indications of a crime, the investigators will look for it. With KYC it will be traced more easily. So there is cooperation between the two parties.