Ahh.. the point is to leave them open ended, at least with the first 2. It not only sees how some one thinks on their feet but, I can hear if they have a passion (or lack of passion) about security or good style. People feel free to go into stories. You don't get this with a "So you have HoA how do you extract the 5th element of 'foo'".
I do not count "wrong" answers against people (unless they are just plain wrong. i.e. all you need is SbyO solutions).
The warnings and strict question, I personally think is a leading question. IMO, as I interviewed perlers it really did help pick out the better programmers. The programmers that had passionate responses to the other questions almost always got warnings and strict right off the bat. They also elaborated on other things they think were important.

grep

grep> cd pub 
grep> more beer