Your Second Issue first:
The [Site Repeat Visit Count] is a Nested Table Calculation,
so the proper Adressing & Partitioning is required
for it to work as expected (to get correct results).
This particular calculation should be partitioned by [Person]
(ie calculated for each Person distinctly).
Please check the Edit Table Calculation dialog
for each Table Calc on my workout (table) view.
Next onto your First Issue:
For counting (grouping by) the results of Table Calculations
using (other) Table Calculations as Bins (group by values),
one could apply a special technique using some properties
of the RANK family of Table Calculations.
For that I wrote two similar-looking calculations --
first one to do the counting, the other one for the filter
(to left only one Mark for each Bin on a view).
Since we wouldn't interested in counting other (non-repeating) Site Visits --
only the repeated ones should be taken into account --
the Bin 0 has to be filtered out, too, hence the second Table Calc filter.
Please find the attached with both views.
Hope it could help a bit, though the solution
may look rather complicated.