Handicap, age, and height will have little relationship to the shaft you need. Height could be an indication on the lie angle of the irons. Shaft would be more about swing speed and impact angle. Your best bet is always to get some sort of fitting. The better the fitting, the better your chances of getting clubs optimized to your game.

That's a loaded question. Pretty much every answer you're gonna get is "Go to a fitting" or you're gonna hear about "what works for me". There are hundreds of different shafts because there are hundreds of different swings. Do yourself a favor and find a good fitter. At the current price of new irons, you want to make sure you have shafts that work for your swing. Not always easy to find a qualified fitter but well worth the effort.
I'm surprised that online dealers don't at least put up a note that they suggest a fitting before ordering.

Get fit. Most places will fit you for free provided you buy the clubs from them. The best place would be to get with a local Titleist fitter and have them fit you. They will be able to work with you to optimize your clubs for your swing.

Our local fitter down here is awesome. Just be open to try anything and enjoy the time.

That is a very good question. And with the information you have provided there is no way to make that determination. Those of us on this site are customers and loyalists of Titleist. We are here to share ideas and make recommendations among our members. "You should visit a fitter". Click on FITTING above and see if there is a fitting in your area and schedule to attend. They can ensure that you get the correct shaft and head. A lot of information goes into getting a new set of clubs, and getting the correct shaft is very important. Most fitters charge and in some cases that charge can be applied to you purchasing clubs thru their event. It is best to get it done right.

Get fit right, and leave out any doubt that it's the swing and not the stick!