It is slightly different is this is a buy strategy vs. sell. 

Should I borrow from my 401K to do my rehab doing the  BRRRR strategy.

What made you change your strategy from buy and hold to flipping?

My plan is to speak with a CPA (which I will do shortly thanks to another BP member here for providing me a contact) to speak about this strategy but I wanted to present this to the community first.

And besides these factors, lies and deceit that are an integral part of any business strategy are wrong.

You could also use the BRRRR Calculator to see if this strategy would make sense.

Send them a letter (not yellow letter because they are getting dozens of them) telling them you found their house to be apparently vacant.

Depends what strategies your existing leasing agent is employing.

I also will be trying to get sellers financing so any strategies on zero/to low-down options would be greatly appreciated.

The flipping calculator is similar but goes into a little more detailMy final piece of advise is to make a concerted effort at defining your investment strategy.