1)
If the maker can exist yet be uncreated, why can't the universe?
Because we know the universe has certain characteristics that point towards it originating at one point. As For the creator, he does not have those same characteristics, so it is much more plausible for the creator to be uncreated.
So who created Allah, did God just pop up from nowhere, one second there was nothing, then there was God?
If God created the universe, he is outside the universe, thus also outside of time. This "time" is a physical construct. A part of our universe. According to relativity, space and time form a 4D space-time-continuum. According to the standardised theory, (empty) space is a physical construct. Put these two theories together, and it would follow that time also is a physical construct, a part of our universe. Speaking in terms of "
one second and the next" is thus an inappropriate representation.