When data is collected from a meter and transmitted wirelessly to the utility, the data contains specific unique identifiers associated with the customers meter number and service address.

These fields are validated numerous times to ensure accuracy before the data is used for billing. This process is similar to the cell phone technology where each cell phone has a unique number that goes with every communication which is used to identify a cell tower and connect your call to the correct location

No, it is illegal and unsafe to do so. Other than some limited exceptions the utility owns and maintains the metering equipment. This includes electric and gas meters used for measurement and billing, and other equipment such as transformers on the ground or on a pole.  Removing or tampering with the property creates a safety issue, which may result in termination of service, and is considered a crime. If done improperly it can result in serious injury or death. Licensed electricians must contact utilities when work requires a meter to be removed, reset, or the power cut or reconnected at a customer premise. 

Details will vary based on the technology but an example is that you will be able to see online usage reports as recent as the previous day. Residential customers will see usage in hourly increments; business customers will see usage in 15-minute increments.