Hey, how's it going?

I have two quick questions regarding mercenaries. I searched through this forum and found several useful threads - such as this Ultimate Merc Guide V3.0 that answered some of my other questions, but am not too sure about the following three questions:

1) How do I find out what aura level my Act 2 Mercenary has when he has Might, Blessed Aim, Holy Freeze, etc.?

2) I found a mercenary guide that states, "Mercs hired in normal difficulty have better final stats than those hired in Nightmare or Hell, and NM Mercs are better than those hired in Hell." Is this true?

3) A lot of threads have members stating that it is best to hire a mercenary at his or her lowest possible level and level him or her up yourself. I thought this was changed some years ago, and that it doesn't matter at which level a mercenary is hired at. Am I correct?

Thanks!
ViC