If this is a mulifamily and things get tough with permits or whatnot it’s a lot easier to combine the second and finished third floors and ask for higher rent then legally changing the house by adding an extra unit IMO with the auditor/city. free to pm if you have any questions.

Where I would start is finding out if there truly are no 2 bedroom houses that have traded in recent time to be able to run comps, I'd then either look on the auditors site and start seeing if there are actually ones with a 2 bed layout, and then simply seeing what and when their transfer price was on the auditors site. 

I started my job in public accounting as an auditor, and recently took a new job a couple months ago in industry doing accounting for private equity funds.

Tax rate- 6% for non owner occupied in SC- use the tax estimator tool from the SC auditor site to confirm your taxes 2.

It's all online on the county auditor's website. 

@Ricardo Ramirez my first instinct would be to look on your local county auditors website, or board of realtors, or even if you have a connection with a title company they may be willing to give you some templates. 

I know here in Ohio you can find most information off of the county auditors' website.

I used the auditor website to contact owner.

Here are two articles that walk through what an IRS auditor considers to be a quality cost segregation study and report.

I am not sure if this question is too broad but are the property valuations on the county auditor site usually very accurate?