Can my iPhone be tapped by police

If you're asking if the police can potentially listen in on your conversations or read SMS and MMS messages, they don't have to 'tap' your phone. It's done at the network level. It wouldn't matter what kind of phone you have. Calls and messages carried by your cellular provider can be 'tapped' with a court order.

They wouldn't be able to place any kind of direct tracking on your device where it embeds in your device, but a legal wiretap order may allow the monitoring of your communications and maybe even a device's location. But that can be done with pretty much any mobile communications device.

Yes

Not easily.