troubled!! in the book they appear to show a few pics of a chassis c/w floor painted green and alli sides showing an OPEN hoop? where rear arch meets but also most others show this hoop welded inn/covered? WHICH IS THE WAY TO GO

Covered, so you can fix the wing to it. Thats what 99% of people have done.

End of the day, it's up to you

Yup, up to you. I didn't bother at all with the hoops, just made some small aluminium panels to cover the holes from the arches overhanging the chassis...

Any photoes of this area just before one would fit the arch and wheel.
Where does the rear panel stop and what happens around the shocks?

This any help?
Rescued attachment ArchMounts.jpg