I guess I'm somewhat confused. If you've already got the Caesar models from the detail design stage, why can't you simply update them with the changes you've found and rerun them?

As far as most of your questions go, I don't think there are any hard and fast rules for any of them, that's what engineering judgement is for - to determine reasonable boundary points so that you model enough of the system to insure code compliance. One thing for sure, you are going to have to have all your degrees of freedom accounted for on both sides of the loops, whether by full anchors, or by combinations of supports, limit stops, and guides.