I said in my reply that you would hear this from the 1BB/hr crew and I say again...it is not that hard to make more than one BB per hour in the games that you play at any big casino from Thursday to Sunday. Anywhere from 6/12 to 15/30 and you should be able to clear somewhere around 200 per day which is better than the managers at all those stores mentioned at the mall. In fact it's better than teachers, cops, firemen, janitors, and lots of other jobs.
Yes you have to give up weekends and yes you have have to be tighter with your money than someone that knows that on every thursday a check is coming but the question was what is the bare minimum...

As for the NL/Limit question - hard to say. More quick money in NLHE for sure but the swings can/will kill you