I purchased the C160 a few days ago and I've been thoroughly enjoying it. I've done a few quick circuits and explored some of the cockpit systems. I'm a fly by the book kind of pilot and I like to keep things as realistic as possible, so I have a few questions regarding normal operations.

1. Fuel predictions. For example, a 300nmi flight with 70% payload. How much fuel including reserves would I need for such a mission? Also, what would a normal cruising altitude be? 

2.  Operation of the fuel valves. I'm confused about the operation of the fuel valves. Am i correct in saying that the fuel in the aux tanks should be burnt first? If so, how would i set this using the valves? During the before start checklist, it states to open the captain's crossfeed valve but not to close it again is this correct?

Thanks in advance for your answers.