You can replace that shaft with any on the market. Since that shaft came with the Ping ISI Irons and had a firm flex, since the W44 were regular, you should get a stiff shaft put in for a replacement.
I like them. The good thing about all the shafts Ping use, is that they have been specially selected to compliment the heads of the club giving the player the best from all their clubs. The AWT steel shafts are brilliant.
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.
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.
Callaway
Yes, graphite shafts are far superior to steel shafts in terms of distance.
Your local golf shop or pro shop should be able to do it, there is nothing too complicated about it. But if they feel they cannot do it, you may have to send it to Ping. Just ask around, I am pretty sure you local golf shop would do it.
Ping Golf started in Redwood City California, but is based in Phoenix Arizona today.
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.
Graphite shafts are very durable and will last for many years without a change in performance. They will however weaken with extended use. Make sure you keep good care of them.
It depends on the butt size of the steel club and how wide the graphite shaft butt is. It is not really ideal to mix the composition of shafts in this way as it will drastically affect the swing weight. Yes it is true there are matrix shafts which have steel and graphite but these have been specifically designed for their purpose and work well. You would be best going and getting steel shaft extensions they are cheap enough.