For MF you should treat it like a business and increase NOI through opex discipline or rent growth factors.

And already have a LLC set up for my Real Estate Sales business.

I’m pretty sure their business is organized to make them judgement proof in case of a lawsuit. . 

We looked into several projects and eventually, I concluded that there is no real reason for me to reinvent my business, other than "just because".

Owning a property with the sister is about impossible as she is not good with money or business minded.

The determination of whether to provide closing presents and how much to spend relies on the agent's business strategy, budget, client connection, and local customs.Good luck!

As a good investor, always always keep this in mind, especially when you get an insane deal, how is the service provider give me an insane below market deal and still keep a successful business running?

There are "interest tracing rules", that can roughly be summarized as the interest on a loan is deductible as a business expense only if you use the funds for that business. 

Your lenders should be willing and able to work for your business.

Very common scam in the US RE space today.. so do be careful what your asking for does not happen in a business setting.