Can I add expense categories to the category list? We want to track our home expenses as well as business. Can I add things like medical?

If on regular QBO not QBSE you can add to the chart of accounts up to the user limits of your subscription. BUT and it is a big BUT - you should avoid if st all possible comingling personal with business expenses in the company file. 

INSTEAD take a look at the FREE-FREE-FREE (did I get your attention yet) personal finance program from Intuit - MINT found at mint.com

This is not a paid advertisement - just a suggestion to keep personal separate