Learn English – What does it mean to be “in suspense”

Gotcha actually has several meanings. All of them can be derived from the phrase of which this is a phonetic spelling, namely "[I have] got you".

• Literally, from the sense of got = "caught, obtained", it means "I've caught you". As in, you were falling, and I caught you, or you were running, and I grabbed you.

• It's a short step from the benign type of caught to the red-handed type of caught. Thus, gotcha is often used when you witness someone doing something naughty.

• Again, it's a short step from I-caught-you-doing-something-you-oughtn't to Surprise! I tricked you! This sense of gotcha is used when someone falls for a practical joke, for example.

• A somewhat-natural progression from the "I tricked you" meaning is gotcha used as a noun: this is a feature of a system (e.g. a programming language) which trips you up or catches you off-guard.

• And finally, from the figurative sense of got = "understood", gotcha can be used to mean "Aha, I see now" or "I understand".

Even in this context is an adverb that is

used to emphasize something surprising or extreme : they have never even heard of the U.S. | they wore fur hats, even in summer. [NOAD]

It is merely a kind of intensifier, usually used to express the outrageousness of a thing. Now let's get down to cases:

Are you even listening?

The speaker doubts you are listening and is rebuking you for your inattention.

What time does the shop even close?

This one's a little harder, but probably someone has suggested the speaker go to this shop and the speaker doubts that it's open, or else someone has suggested that shop may be closed but the speaker is emphasizing the fact that the shop in fact stays open quite late. It would depend on context.