If you run out of ammo, wait 30 seconds and your ammo will completely fill up all of your weapons.
If you buy an Exotic engram from the Exotics merchant, it is a guaranteed Exotic item. But it is not guaranteed to be an item for the class you are using.
If you buy an Exotic engram from the Exotics merchant, it is a guaranteed Exotic item. But it is not guaranteed to be an item for the class you are using.