Cooking newbie here.

I don't really drink but wanted to try cooking with wine. I researched it a
bit and realized that wine doesn't really store well after it opened but
supposedly it is still fine for cooking.

Can anyone clarify this? How long is opened bottle of the red wine can be
stored in the fridge and still be fine for cooking?

Also I understand that opened wine turns in the vinegar. So maybe I am
better off just buying vinegar for cooking?
Does vinegar produce the same results as wine for deglazing for instance?
What about the other uses when recipe calls for cooking in wine?