definition of taxable income in capital gains tax computation

I am looking into liquidating highly appreciated equity (stocks exercised from iso of my last employer) that will fall under long term capital gains over the coming years.  After doing online research I have come to believe that unless I move away from new york to say FL (other states with 0 income tax) I can't avoid paying state income tax on any of my capital gains.  For federal I found information that for joint filer like me if I may taxable income is below say $72,000 I pay $0 federal capital income tax.  What is not clear is on what it means by taxable income of $72,000.

 

1) Is this all salary we get by working for another company? 

2) Will any amount from the stock liquidation will be taken into account in taxable income?

3) Is $72,000 after deduction like employee contribution of eg $18,000/year 401k, $6000 health saving account, or before contribution?