A second meter may incur a second customer charge and billing. Depends on where you live and the utility company. With the potential load in the new building, if it would potentially overload your existing run, you can either do what you plan, or upgrade the service to the house, and then run a subpanel from it to the new building. If the existing panel can't handle the load, then it would need to be replaced as well, so that may factor into it as well.
See what the pros have to say, as I may have missed something here, and maybe call your utility company. If you can split the service after the meter, then run it to the existing panel and to the new building, you wouldn't incur a second customer charge. Not sure if that's okay or not.