Do they sell lemons and lemon juice?

Yep

Yes

Sometimes cuz stuff always changes

They do have a small grocery area but the items there are not consistent. You might find lemons one day and a week later they won't be there. I think it's really whatever is in season. Also everything isn't $0.99. Now it can be 1.99 2.99 Etc. If there's no price on the item, it is $0.99 otherwise it's whatever it's priced on the tag.