Hello Jerry, I want to preface by saying that I am not a CPA and that you should definitely have a CPA with experience in RE because they would be able to answer these questions.

But yes, you should have a CPA, and the one smart enough to properly prepare your taxes over the years should have an easy handle on this too.

Cost seg studies have many different price points, depending on the complexity of the property but I would budget a few thousand dollars for a property the size.Regarding material participation, you should check with your CPA or tax advisor but generally speaking yes that would be enough time.

It should be, but I would double check with a CPA knowledgeable with STR.

Not a CPA though, this is just internet banter not tax or legal advice (disclaimer, I’m not a tax pro so speak to one about your individual situation).  

First - Have a conversation with your CPA to see if will be beneficial. it appears that you are unsure based on the phrase "hoping it would benefit us".

You would need an attorney and CPA on your team beforehand who understand what you're trying to do before you sign the paperwork. 

Do I just need CPA?

When you submit your income and expenses to your CPA it should be documented that you did not receive 5 months of rent plus your attorney fees which you should have receipts for. 

If you have questions on what qualifies for something that can be depreciated then please get with your CPA or just google it some.