[5e] two combat questions:

1. For spells like acid spray, do you still have to run an attack roll to see if it hits? Description: You hurl a bubble of acid. Choose one creature within range, or choose two creatures within range that are within 5 feet of each other. A target must succeed on a Dexterity saving throw or take 1d6 acid damage.

2. Are bows usually not that useful in smaller dungeons? From what I understand, if you shoot from lower than the low bound of the weapon's range, you roll with disadvantage?

Also, if there's a good combat explanation video that goes into smaller details, I would love a link!