for the first one i think you can use the top nav-bar link and pick a date-range, then filter descending by views. like so:
https://meta.discourse.org/top?order=views
of course that wouldn’t limit it to 100 (presuming one uses a time range that shows 100 or greater).
a data explorer query would be the way to go. there are a most active lurkers query and a most active 100 topics query included in the defaults.
this is a great topic by the way, thanks for posting @Bas 
i’ve always taken the approach that every active forum member starts out as a lurker. i know i usually do.