a) Regarding the 50-stock limit:
With the complete (free) version of ProRealTime, the screener can display up to 50 results.
With the Premium version, this limit increases to 100 results.
If your filter matches more than 50 (or 100) stocks, you can work around this by adding a secondary filter to reduce the universe.
For example: if you get 75 matching stocks, you could run two separate screeners:
That way, you can capture all signals in two batches.
b) Regarding multiple sorting criteria:
Yes, you can display and sort by multiple variables.
In the free version, you can sort by up to 3 columns.
In the Premium version, you can sort by up to 6 columns.