Hi
I think the different courts are best explained via the link you gave to Norfolk, "Church Courts - probate records before 11 January 1858". Certainly better than I could!
As you have said, the ANF register copy wills are locked up as far as home viewing is concerned. I don't know why that is as we can see the Norwich ones.
But at least it appears that we can see the ANF copy wills for 1800-57 on Norfolk Sources
i.e., from NROCAT
Fidgett, Jane, of Fakenham, 1808
ANF will register 1808-1810 (1808) fo. 12 no. 6
Chose that one at random, but anyway it is online. Can't get the Rootschat Shrink Link to work for this!
http://tinyurl.com/y5db2n6l