Hi Advil - Thanks for your post.
Re your questions. If you view my other youtube videos on the subject last year - or you may have already? there is information on some of this.
Just quickly. I may offer a premium model with a Carbide stylus tip and a economy version with a hardened steel ball tip - still very durable.
A broken stylus would be very unlikely ....but I agree with your point and plan to offer replacement stylus assemblies for a reasonable price.
In order to keep the price down I plan to only offer the mechanical touch type at this stage.
Cheers Keen