Also, if that asset is a primary residence that meets section 121 guidelines, is the first $500,000 capital gains exclusion amount disregarded in determining these brackets/tax rates?

If you held it for less than a year, it will still be taxed at ordinary income rates (short term capital gains really just means ordinary income rates).The fact that it was in a single-member LLC does not really matter; it will be taxed as if it was in your name because the federal government disregards single-member LLCs (pretends they don't exist).

If it's a single member LLC it will likely be a disregarded entity for federal purposes (so not really changing your federal taxes when compared to holding property in your individual name) but you may have higher costs at the state level. 

My guess is that the C corp has it's own tax id and has filed it's own taxes so it can't be a disregarded entity.  

This is disregarding any Asking price. 

Totally wrong: it's not more expensive than to operate as a person vs LLC, for tax purposes it's a disregarded entity if you're 100% owner, loans more expensive because it's commercial loans not because you're in form of LLC, no annual fees at all.Pros: your name is not searchable on auditor site, it's give your assets protection if you're not co-mingling money, you can build separate credit history for your LLC (for example, I have 2 credit cards for my businesses and they are not on my personal credit report - just on EIN).Depending on how you structure your businesses, you might decrease taxes - rental business is on sch.E while main business on sch.C and you can manage cash flow between them).Besides, it gives your money protection from claims on your personal liabilities (unless you QCD your properties back and forth to get a loan). 

If the LLC is disregarded then you would be the tax payer on both counts and would in essence be trying to buy your replacement property from yourself.  

I still question, that if I am paying for their "accidents" that i should not have to pay for due to their disregard, can that come out a security deposit?

Please disregard my "vote".

1,2) Every book says that a LLC (filing as partnership) is a disregarded entity for tax purpose.