If it makes sense to claim the standard deduction, do I still need to submit detailed records of what could've been itemized deductions? 

Find out what sheets you need to submit for a garage conversion to ADU.

I didn't need an ITIN till I submitted my first tax return with the IRS. 

But only speak with local owners with which you have a pre-existing relationship.Through your investigations, you should have a clear picture on the owner’s reputation, which will give you an idea of the quality of the asset, and the owner’s motivation, which will allow you to evaluate the risk points of the deal and submit the most competitive offer that is curated to fulfill the seller’s needs.

It was listed at $79,900 and I submitted a low ball offer at $60,000.

Generally you need to submit an application with your goals/intentions accompanied with a depiction of the land (a screen shot of the property from Google earth should satisfy).

I have submitted several posts (each flagged for removal each barely after I'm done submitting the post) removed before I barely submit them.

If you accept, the entity that you are requesting information from has 30 days to comply and fulfill your request from the date all monies are paid and you have answered any/all questions they have about your request.If they deny your request, you are more than welcome to submit a modified request.

If they were not submitted, you could try to demand that in the purchase.

my process is similar, but differs a bit. 1) They fill out the application and submit it (I use Cozy, but whatever works). 2) I use the application to (internally) make a decision.