The answer to your questions is "it depends".
You may be able to work part time depending upon how busy your state-required sponsor/mentor is and how much work they assign you. You also should be prepared to work for free or even pay the sponsor/mentor for training you. You are assisting them while they are training you so maybe you can work a fee split arrangement. Most folks can almost qualify for food stamps while going through the two-plus years of qualifying experience needed to obtain the basic (or lower level) appraiser license.
As for location, the more active your real estate market, the better chance you have of earning an income from appraising. Just be aware that your costs never go down but the fees you receive may not rise to match these increases. Most appraisers I know haven't seen a real fee increase in almost ten years and the analysis and reporting requirements (read: workload) have increased substantially over this same ten year period.
I suggest you read more at these websites:
www.asc.gov (the Fed Gov's appraisal oversight committee) and
www.appraisersforum.com (the leading appraiser forum website).
Best of luck with your decision.