Why would it include personal income tax? Your tax situation could be different than mine (single vs. married, deductions AKA children, etc.) it would be impossible for the employer to know what you personal income tax is going to be. Insurance? if your spouse has access to a better insurance policy you might opt not to participate in your employers plan so why would they "include" that? Social security and medicare AKA FICA? they pay half, you pay half and the rate is easy to find (7.65%, except this year) 401k? well you are paying yourself there, it's still your money.
You fill out a form when you begin employment that specifies how much to withhold: http://www.irs.gov/pub/irs-pdf/fw4.pdf
Yes, but that is typically after you have accepted the job, not before.
yes, but read the question above.
In Europe some of those things are paid through taxes and some are not. To make a reasonable comparison you need to know what's included each system and how the fees are arranged.
At the top of your paycheck you would see your 'advertised' earnings for that period and then at the bottom you have your take home net pay. Depending on your location, you loose around 20% of your 'advertised' pay to taxes and other mandatory things. If you contribute to a 401K you loose even more.