Confusion over using 401(k) money

[Account Closed]

I've been reading a lot about using a self-directed 401(k) to help with funds for a buy & hold rental property. There are a few things I'm a little confused about. 

1.) Everything I'm reading says you can use a "self-directed" 401(k), which I'm assuming is NOT a 401(k) account from a current W2 employer?

2.) If so, can you roll over those employer 401(k) funds to a self-directed 401(k) and

3.) Most importantly - How exactly do those funds help finance a rental property? Are you using it for a down payment? Is it a loan you have to pay back or are you "rolling" it over into another investment account (real estate) to avoid tax penalties?

Much appreciation in your responses.