"- I am still confused about filing the tax. Referring to Airbnb website (link below) we have to pay tax if we have more than 200 transactions AND make over $20,000. So if I did not have 200 reservation, would I still file the tax?"
Yes. Definitely yes. There is a difference between a company (AirBnb) being required to submit a 1099 and an individual (you) being required to pay income tax. In brief, if you make income, with rare exception, you have to pay tax on it. Not receiving a 1099 is not the same as being given a "pass" on the taxes. It simply means that AirBnB isn't required to submit paperwork on a zillion (relatively) little transactions. If you don't claim the income you are committing tax fraud. You have to decide if you wish to take the risk of audit.
On expenses to report...calculate the square footage of your rental space as a percentage of your total property. In my case our carriage house is about 12%. If its primary use is rental income then everything that is used to support your rental space is deductible. So 12% of my property tax, utilities, property insurance, plus all direct expenses are deductible. It's much like having an office in your home. I have been told it's an audit flag but if you do your taxes honestly it shouldn't be an issue.
Hope this helps.