I have 20 some years under my belt having tried probably every variation that there is. I have even filled the entire shaft with lead in my experiments. I will boil down my hard learned lessons.
"OK so I have a metric tonne of questions to ask about shafts"
A Your swing is a bazillion times more important than your shaft. Spend far far more time perfecting your swing than even thinking about shafts at all. Let the shaft force you to deal with it via an issue that surfaces that you cannot ignore otherwise ignore the shaft.
Q 3) How does the length of shafts affect shots.
A Length is far more important as a comfort factor in your wedges. Your Driver should NEVER be over 45 inches unless you are prepared for disastrous consequences and the lessons you will learn.. I have played with plus 8" (trigonometry said so) and was fully willing to suffer what may happen. I am now thinking of settling on my driver at women's length and my wedges plus 3 The plus 3 forces me to use a 6 degrees flat lie for the clubs (if plus 3)
Perhaps this WE I will break out the saw and shorten them. Length is not your friend. It is required but should be as short as possible for comfort (wedges) and distance maximization needs some length on the longer clubs.
!!!!!! sweet spot % on longer clubs is often better at shorter not longer length so more distance is the result. Longer requires serious physical skills and training. The average length of pro players who's income depends on scoring is about 45" (44 1/2)
Q (1) What will a shaft hit like if it is too stiff?)
A I am am going to experiment with women's flex STEEL shafts for my longer clubs. I am seeking a more pronounced loading action to take place. I swing my irons at about 90 mph or so and according to the "book" I should be using regular or stiff flex. I remember in 1989 using a women's set and feeling a distinct flex/loading sensation. I will NOT be using women's flex in a graphite shaft. graphite twists too much if "whippy" Too Stiff any shaft will cause you to not get any flexing, a subtle loss of connection or feel of the club head, perhaps less twisting and less spraying shots all over for more accuracy if you are an aggressive hitter.
Your swing is a bazillion times more important than your shaft. Spend far far more time perfecting your swing than even thinking about shafts at all. Let the shaft force you to deal with it via an issue that surfaces that you cannot ignore otherwise ignore the shaft.
But if you must then this is the only resource that you need to study. Mine is very worn form constant referral. About $10.00 http://www.amazon.com/The-Golfsmith-practical-clubfitting-program/dp/0913563056