How do I "line up" financing before submitting offers?

[Chris Haas]

I've read a lot of the forums but haven't found my situation.
I'm credit worthy 716 was my recent score when I switched credit cards.
Strategy is buy / hold long term rental. Price targets 80K to 120K.

I have about 20K cash to use, and 50K Home Equity Line on my current house that would be available as well.

My questions:
Since I have some available cash, how do I use it most effectively?

Can you get preapproved for a $$ amount like you can when shopping for a personal loan?

Most common scenarios I hear about are roughly 20-25% down. I see FHA thrown around a lot I need to understand if this is valid if I don't plan to live in the property. I am assuming it is not.

Advice / Links appreciated, I keep googling only to find sales / marketing for get rich quick schemes.

Thanks for your time
-Chris