You should use unsalted, but If you only have salted, subtract 1/4 tsp salt from the recipe or it will be too salty

Sweet (unsalted) always unless recipe specifically asks for salted. You can always add salt.

You can use either in baking. Lately, I'm finding I like baking with salted butter better. It only adds a negledgeble amount of salt. Recipes from older cookbooks where the type of butter isn't specified or they give you a choice of butter or margarine, used salted butter because margarine has salt, so the recipe has taken the salt in it into consideration.

unsalted, if you have it on hand.

Use what you have around.

unsalted.

I don't remember the last time I bought salted butter. I use unsalted for everything so that I have control over the salt content.

Unsalted for Baking, otherwise I usually use salted because that's what I have more often.

Unsalted for sure! You can always add salt, can't take it back out though ...