Welcome to the boards! I am a long term lurker... infrequent poster myself.
The best refinance mortgage calculator I have seen is the following:
http://www.zillow.com/mortgage-calculator/refinance-calculator/I may have made a mistake while inputting your numbers, but it looks refinancing will save you about $50k if you are paying your original mortgage at the normal schedule.
If you are paying down your mortgage with an extra $1,000 a month, I'm not sure how that shifts your existing payment schedule/interest.
Also, after all of my research done online/boards. There seems to be no concrete answer on whether or not you should pay off your mortgage early or put the extra cash into the stock market. You will make more money in the long term if you go with the spare money in the stock market based off of statistical averages. BUT there is a price, which is hard to quantify, for owning your home outright and the peace of mind of not having a mortgage payment.
Personally, I have flip flopped on the idea of putting money in the market vs. paying down the mortgage. I used to think the stock market was the best, but then I realized that by the time I retire early, if I own my home outright, it reduces my annual expenditure significantly and allows my long term capital gains taxes to be 0%. (
http://www.bankrate.com/finance/taxes/no-capital-gains-due-for-some-investors-1.aspx)
Good luck either way! This is an excellent problem to have!