My first official giveaway! [ENDED]

Alrighty people! My last thread apparently was a flop, so let's do this differently, puzzle time.

This is for Hacker Evolution Duality, so people don't waste time if they have it already. =)

Format is steamgifts.com/giveaway/XxXXx/

The bonus was claimed, however the drawing is still open for a few days!

Good luck everyone!

1. 2.71828183
2. You might go see one to deal with mental issues.
3. The letter representing the number of fingers you have.
4. Do you know him? (Clue: Frank Zappa and one of his friends did a song all about him)
5. Mr. ?

Well now, it's all done, haven't gotten a hold of the winner yet, so I won't name names, however here are the answers if anyone is curious!

1. E constant - pretty obvious, easy to google
2. psychiatrist
3. X - roman numeral for 10
4. Muffin man - Do you know the muffin man? Frank Zappa and Captain Beefheart did a song all about him!
5. Mr t - I pity the fool!

Thanks everyone who tried/entered! I learned a bit more about what and what not to do. =)