I will just try to explain the confusion. It is because when you ask did you receive it, you are asking if that did something in the present. If this doesn't make any sense, it's okay because the english language is like that sometimes.
It has always seemed natural to me. I am fine with that though. it would be annoying to type with all caps, but I actually like to type with all lower caps. my roommate used to type papers like that.
Yes they are interchangeable. Upon is more formal though. I would use upon in writing and when talking to adults. When you are with friends or sending a text saying "on" is fine.