you should create 2 separate instances of PowerStore, one for the purchase and the other for the quote.
No the flat rate shipping amount cannot be easily edited by the customer.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.