The government SS site is pretty good. www.ssa.gov
There are a few calculators there. I think you would need the most complicated one, which is a download, to do the scenarios you describe.
All the formulas for retirement benefits are based on your highest 35 years of earnings. It doesn't matter the order in which they occur. If you have fewer than 35 years it will include some zeros to make 35 years. In order to qualify at all you have to have 40 "credits" which is basically 10 years of work history.
Don't know about whether the answers from the SS site are in today's or future dollars, but I bet if you did some research there the answer would be readily available. I think they're in today's dollars, but don't quote me on that.