@Redbird11, way to go on getting your first RTA build going.
Popping and crackling.
Crackling while you are taking a hit is 100% normal. It can be heard more loudly on some RTA's versus others. It means things are working as they should be.
Popping is another matter. If your atty has sat for awhile and you take a hit you will get a single "pop". That is perfectly normal.
If however you are getting continuous popping throughout your hit then it is the wick. You don't have enough cotton in your coil.
With cotton you want enough of it in the coil so you "feel" resistance when you move your wick side-to-side in the coil. If you feel very light resistance then you do not have enough wick. If your coil is visibly moving, or distorting it's shape and set location, when you are inserting your cotton wick then you have too much wick.
There is a balance you need to find. You will get it.