@Bruce P. Hey Bruce, a GC/developer here so I am speaking from experience. The as-build from architectural plans normally would not call out the type of Appliances/countertop/ backsplash/ tile/vanity. Or sometimes, things are missed due to human errors. It is ALWAYS better to leave it out the soft cost items so the "owner supply the material for finishes". Or hire a designer and be as specific and detailed as you can so you have minimal change orders. Items like lumber, insulation, roofing would be categorize as hard costs. Soft cost item would be the tiles, cabinet, appliances, designer items, some finishes...etc.
By law, no more than 10% downpayment should be required. If the GC asks more than that, be very cautious and ask for all the right questions like their license, experience and insurance coverage. Make sure to check out their job site! Furthermore, your GC should have enough money in their account to cover at least 10-20% of the work. And make sure you always ONLY pay per progress, NOT ahead.