I play a Warp World and reveal a Null profusion and a Price of knowledge, what is my handsize? The gatherer rules for Warp World state that revealed cards enter at the same time, so their time stamps are the same. So my question is which one goes first and what is my hand size then?
Assuming you're casting Warp World on your turn—since it is a sorcery—you get to choose which order the effects apply. If someone else cast the Warp World on their turn or you used something like Quicken to cast it on someone else's turn, the person whose turn it is would get to choose.
613.6j If two or more objects would receive a timestamp simultaneously, such as by entering a zone simultaneously or becoming attached simultaneously, the active player determines their relative timestamp order at that time.