What are common ways of financing for a home in the 300,000 range?

I’ve honestly never looked into real estate. I grew up in an apartment all my life.

So I would be delighted to understand how real estate works :D

1. for a 300,000 dollar home how much should I be able to put on down payment?
2. what do you think the average monthly payment would be should I finance a home without purchasing it all at once?
3. what are common, “home plans”?

Thanks so much.