Purchasing the LLC gives you ownership of the property, but it also opens you up to additional legal exposure since the entity has been active, and there is no way to really know for sure what else they used the LLC for.

@Drake BackmanBigger Pockets is a great place to find a tax strategist specializing in real estate taxation.A good real estate tax strategist can save you thousands of dollars by leveraging entity selection and formation, tax deductions, cost segregations, bonus depreciation and tax planning.I recommend finding a tax  strategist specializing in real estate taxation, business taxation, financial planning and tax planning.Consider working with your tax strategist remotely to expand your options.I would also recommend looking for a tax strategist willing to work with you throughout the year.

If you know of any legal entity in TX that can help in a case where GP is not doing their job (maybe a branch of SEC), please let me know.TIA

If it's a QM you won't be able to close in a business entity like a LLC, although in some cases you can transfer into an LLC after closing.

What types of IRS/CPA approved payments are working well for rents to LLC entities to keep personal and business funds from co-mingling? 

If you continue filing taxes jointly the income you realize from your separate property will still need to be explained and redacted, regardless of the type of entity holding the real estate.

Question 2: Is it a good idea to put every piece of property into a separate LLC entity (1 for 1) or is it okay to put a few properties into the same LLC?

@Brice Alef-Torrisi, there's lots of different ways to skin this regarding entity structure and financial account structure.

For separate entities I use separate files for each entity.

They need to be owned by a different entity, such as an LLC.