I’ve heard of folks borrowing from their personal network for a down payment, but is this actually used in practice?

Since you are just graduating college you may already realize that it's not what you know, but who you know (as a personal note, I had college friends that were barely passing their classes however they ended up with really good paying jobs due to "who they knew").

Meanwhile, with the person who foresees themselves mantaining their W2 job, this entry step is not necessary and truthfully should be avoided.

This really depends on your market, personal finances, and risk tolerance.

That’s a personal question, but time is money!

You can look up cash buyers on propwire free, and reach out to the LLC owners by looking them up, or call the agent and ask them.Another option would be to find some private money lenders, and get them to go down on a hard money loan with you, unless you can get all the capital from one person alone (this is very difficult because most people won't loan that much to someone new to real estate). 

Each person can provide their own definition of freedom.

Personally I'm not a fan of getting pressured into a deal - if you don't feel good about rushing into the deal, it's better to back out.

As an investor myself there are certainly areas I wouldn't personally buy.

I also have a 12-door rental portfolio in Detroit.I personally would NOT sell your primary.