In general, if you have income then you must file. That includes stock dividends, rent paid to you by your tenants, and pretty much any other form of income.
Whether you are actually employed or not is irrelevant. It’s income tax, not employment tax!
Yes. If you are renting your house you will want to do the taxes right and take advantage of many write offs and deductions. Keep track of all your expenses. If you get an old copy of Turbotax and run through the Q&A sections for rental property you will learn a lot. Next year you will be ready to do your own taxes.
If you handle your rental property correctly, you might have a net loss from the activity. In other words, it may be more beneficial for you to file than not to file.