Squatter are ejected and competitors displaced.

Even in my low C-class apartments, I do not rent to anyone who has been successfully evicted, with a record including "an ejectment" (tenant forcibly removed from the rental property by a Pennsylvania constable) and unpaid rent, anytime in the last fifteen years.

And does any one know of any law offices who has proven to be successful with ejectments?

If the homes have residents, you will have to file an ejectment lawsuit against them.

Is step 1 the ejection notice?

There is a 10-day demand for possession, but that is given because if the borrower fails to vacate within time limits, he/she forfeits their post-foreclosure redemption rights.The appropriate lawsuit is ejectment, not eviction.  

Either some form of an ejectment order or an eviction.

I would hesitate myself to have an ejection pump system with tenants. 

See also Need recommendation for attorney to file summary ejectment. topic for other options.

I could possibly avoid filing a summary of ejectment and directly go for the writ of possession.