I may have based my answers on some assumptions. I’d say if you are just starting to dive deeper into pillar 2, it’d be better to try to learn more broadly about what can be done with it before considering specific implementations. A few searches on the forum may land some useful bits of considerations in regard to contributions, buy-backs, pledging vs withdrawing, withdrawal upon going abroad, vested benefits and 1e. Pretty insightful reads.
We probably need a Wiki topic on the Pillar 2. Best non-wiki topic I’ve found is this one: What about Second Pillar?
Compiling what we currently have would require quite some time and energy, I’m not really up to it right now. Maybe somebody else would like to tackle it (possibly for their own blog, the task, if handled comprehensively, is big enough to warrant some reward 
).
As for pillar 3a, we do have a Wiki topic for it: The Pillar 3a Tutorial
Feel free to point out any discrepancy, outdated or lacking information.