>> better Pens <<

There are some for the wacom and many for touch screen including a
number of multipoint pens which include a touch screen stylus.

>> and how often and why do you change the tip? <<

not often if you have a light touch and keep the tip absolutely clean...
I have several styli which I have used for years but I often see users
who think they have to press hard who will not only need a stylus, but a
new screen cover in short order ;-/

Every couple of years, I'll get a piece of grit on the tip which I
normally feel immediately the first time I touch the screen. You can
remove and clean, but the scratch it leaves will be there forever.

Beverly Howard [Microsoft MVP-Mobile Devices]