Might be moving to a different country and had a couple questions about región locked dlc and more

I will probably be moving to Ecuador and had a couple questions.

1) I plan on buying Horizon Zero Dawn: The Frozen Wilds an I currently have a US account, would I have any problem playing the game or dlc over there?

2) Once I move over there would I need to change my region to that country or region? Can I change that if I move back to the US?

3) If i keep the the region as US, would I have to buy my games online? Since if I buy them over there it'll be locked to that region right?

4) is the ps store based on where the account is or the actual system?

Sorry for any dumb questions just making sure I understand everything correctly. Thanks!