Submit A Question about KLOM Key Cutter

Hello,
for what kind of key blanks the cutter is purposed? Only brass and aluminum blanks or is it also possible to cut the blanks made from more rigid materiel / alloy? Like the blanks of Silca for example.
I your discount price of US$44.99 the best price you can sell it for?
Will it be delivered with the little bag like seen on the pictures?
How many keys can be cut with this cutter approximately in its lifetime to your experience? If it will become dull someday, are there any spareparts available or will I have to buy a new piece in that case? On the photos it looks like the blade of the cutter is exchangeable.
Thank you very much in advance for your effort and have a nice day.
Best Regards
Olli