I wish I could know everything ever, like that would be my wish - that's what I hope heaven is, that they tell you who shot JFK and all that stuff.

The speaker is expressing a desire to know all the secrets of the world. They suggest that knowing all of these secrets could be what heaven is like – including who shot John F. Kennedy, and other pieces of information which are currently unknown. The speaker seems to suggest that they hope they will find out these secrets in heaven, if they go there after they die.