If you were properly fitted by a certified Titleist fitter, you should trust that he/she knows what they are doing. It is not really possible to tell you what shaft to use based on swing speed alone, there are just too many other factors involved.

A "hard" or "soft" stepping is done to a shaft to change the flex slightly. It is usually used when you are in between shaft flexes. It is also called "tipping" by some people.

Hi James, Yes, we will use an 8 iron shaft to build your 7 iron and will butt cut it to the 7 iron length (minus 1/2"). We would assume that your fitter had you hit both the R flex as well as the S flex and determined that an in between flex would be most optimal for launch and spin. The hard stepping of an R flex will make it play slightly firmer than the R, but not as firm as the S flex.
As far as speed, yes, this would be in the ball park, but each individual loads the shaft slightly differently and your fitter can show you why it is the best choice for you. We would recommend that you ask your fitter these questions as he could explain his reasoning for the selection of shaft as well as the hard stepping.