For the length, the best way to figure this out would be to find out how long shows were in their original broadcast form, and subtract that from how long they were allotted to run. If the info itself isn’t available, versions available on DVD or on official streaming sites might be usable–though make sure they didn’t add back any scenes cut for time, or cut something that was removed from syndication.
For the number, it might be possible to tell with cuts and/or old recordings. Still, it would probably have to be data we’d have to collect.