Hi Ash,
I did write a lovely long response unfortunately Moz decided that it was going to remove it so here goes attempt two!
Let me start by a comparison to Facebook. On Facebook you have your personal page which you interact with etc. and you have a business page which people "like" etc. and find info. The same is essentially true for Google+
G+ you have your personal account which can be set up to contribute to websites ( rel=author ) telling people you've done stuff on that site. You have your business page (rel=publisher) which people +1 and talk about the business. The publisher page also can interact a bit more with the SERP. Unfortunately publisher is not as easy as author but they do act differently.
Now you don't really want to have a business set as a "personal" page as it doesn't have some of the features and also doesn't look as professional.
In short:
Use your personal account for rel=author on your site telling Google what you've made on the site (E.g a Blog)
Use a business account for people to +1 and recommend your site as well as interact with your customers
I hope that helps anything else you need to know I'll do my best to help.
More info :
http://www.google.com/+/business/
http://www.google.com/+/business/brands/get-started.html