Or what if the investor finds the deal and you make double what you normally do on flip because it is a great deal?

Depends on what's normal in your market.

I also leave enough pieces of the pie when a contractor is finishing up.

Safe and normal or ultra risky and dangerous?   

The house has two restrooms, a normal walk-in shower in the master, and this tub in the main bathroom that everyone would be using.So I’m debating if it’s worth it to pay the money to remove it & replace it with a normal walk-in shower because it would be more convenient for potential tenants.

This is a list of all the paperwork I plan to collect so far:1) IRS Form W-92) Independent Contractor Agreement3) Scope of Work4) Payment Schedule5) Insurance & Indemnification Agreement6 ) Lien Waiver (after work is completed)(I have already gotten their license and insurance information)For the experienced flippers out there -- are there any other documents you normally collect from your contractors?

But be prepared for that significant time commitment unless you're planning on using a property management company, etc. which takes another slice of the pie, so to speak.

Yes, I think normal cost seg studies cost a few grand. 

When the Fed affirmed the market’s assumption, trading of the 10yr Treasury continued on as normal, and in this case, investors sold the 10yr.

Normally, when you sell a property and keep a pre-existing loan, it is called a Wrap.