Depending on your filing status, capital gains tax rate goes up to 20% from 15%.

(b) Required Documentation (i) Limited or No History of Rental Income Where the Borrower does not have a history of Rental Income for the Property since the previous tax filing, including Property being vacated by the Borrower, the Mortgagee must obtain an appraisal evidencing market rent and that the Borrower has at least 25% equity in the Property.

Lenders won't let you add any rental income from the STR until you have that income filed on your most recent tax return. 

Make sure to open a separate business account for the LLC to avoid co-mingling personal and rental funds.Unless legally required, avoid getting MMLLC as it requires you to file a separate tax return.

@Keith Cuddeback The deed of trust will be filed with the county recorder's office and will identify the original amount of the loan. 

But here's where to start your research in Dallas County: General Procedures for Filing an Eviction for Non-Payment of RentI also can't answer your second question successfully from my perspective.

And yes, it must be filed. 

But if you plan on doing more spec homes, the LLC would likely offer more benefits through legal protections (obviously speak to your attorney about this) and potentially tax savings if you look to file as a S-Corp.

I already filed my 2022 taxes.

@Michael Turner Yes, you can combine time to meet material participation requirements if you're tax filing status is "married filing jointly".