Be very careful, depending on your state, it’s very hard to get clear title for tax defaulted properties, you usually need wait redemption period expires then suit quiet title for marketable title

How does this work usually.

It's very common for small business owners to understate their expenses and overstate their income.The overstatement usually is in the form of "We don't run everything through the cash register", especially in a cash business. 

Yes, you certainly need insurance, usually a Builders Risk policy.

Make sure that your listing has pictures (the more professional looking, the better) and a great description.

Is this usual.

Many Private Lenders are offering the initial costs can add to your primary loan but it is usually for one year but might be a good solution. 

"They were renting out their home"These are usually the worst type of landlords.

Actually, getting a new mortgage usually causes a short term drop in your credit score, then an increase in your credit score in the long run. 

In our state, an evicted tenant, or one that has abandoned the habitat has 30 days to remove their personal property.There are also usually  caveats in the L/T laws that allow you to post a x-day notice of Abandoned Property.