Yes. Supplier has rich experience to support customization based on specific requirements description or drawings. But may charge mold fee for some special  products. 

50pcs. We usually require 50pcs for each item, but sometimes the MOQ is 20pcs for some large products especially for sheave and Bushing. 

Yes. It is available to check quality first. But usually the lead time is about 20 days.

Yes. We have stock for solid collar and some split collar. But we usually don't have stock for sheave, bushing and Hub.

It usually need 70 days, but it may be shorter for Shaft collar. It depends on our production schedule.