Thanks for your enthusiastic approach! Here is my comments regarding your questions:
Where can the shop get his warranty?
Orginally, Globalsat will offer the warranty to dealer, it depends on contract.
Where can he send the broken stuff to?
It depends on contract. Germany has one station or dealer can collect deffectives back to Globalsat for repairment.
Where can he order from?
Just contact to Globalsat.
How long after a request for a product they have to wit for arrival?
Depend on lead time. Offically, it is around 6 weeks includes production.