Get whatever you want to get! You will find the best thing to do is get custom fit, this will tell you what clubs are best for your game. You are quite short, so you may need to get an inch or so taken off the length of the clubs.
Callaway
currently Fujikura but they have used others
Yes, they can. However steel shafts that are long enough to be a driver shaft are very uncommon, this is because they are so heavy and not as good as graphite ones. If you find a steel shaft that you would like put into your driver you will need to check the tip diameters are the same and your local pro or clubmaker should be able to do it for you easily.
Callaway clubs differ from other clubs because they have bore through shafts. These can be difficult to put in, so you should really get your local pro or clubfitter to replace them.
Callaway Big Bertha irons are a line of golf clubs. These clubs are available with either graphite or steel shafts. They tend to be great for players who have high handicaps and are very forgiving and thus mask bad swings well.
Young children should really use graphite shafts, they help them get the ball in the air easier and they are a lot lighter than the steel ones. Any clubs I have seen designed specifically for children have graphite shafts. When they get a bit older and stronger say 13-14 they may be able to move on to steel, because their swing speed will have increased and they are a lot stronger. Girls however tend to stay with graphite as they have slower swing speeds and the graphite shafts help get the ball in the air.
Graphite shafts are lighter and more flexible, which can help increase swing speed and distance. Steel shafts are heavier and offer more control and accuracy due to their rigidity. The choice between graphite and steel shafts ultimately comes down to personal preference and playing style.
If you want a high quality shaft, you should look along the lines of UST, Grafalloy, Aldila or Mitsubishi. I cannot tell you which one you should get because I do not know your game/age/ability etc. The best thing to do is to go get custom fit and try out a few different shafts. Nearly all shafts have different kick points and produce different launch angles. The problem with Callaway clubs though is that shafts go through the head to the bottom of the club, some golf shops may actually shy away from fitting new shafts to these.
Yes, graphite shafts are far superior to steel shafts in terms of distance.
1996
The majority of them would, but quite a lot still use graphite shafts. Graphite shafts help launch the ball higher with their slower swing speeds.
There are extensions you can insert in the butt end of the shaft (after removing the grip) that can be trimmed to the desired length and re-install the grip. This must be done carefully, as some graphite shafts can crack easily.