Late to the Party and Stuck in a Time Bubble, need advice

Hi. I'm an old player and quit playing after a few cycles but collected data packs and the big boxes until stopping at Mumbad.

I'm recently just collecting again and managed to find a Reign and Reverie, the new core (I realize the new core might already have cards I own but Netrunner is extremely scarce in my area and I wasn't taking chances), and only a few post-mumbad stuff.

I found a pretty niche community that's just starting to like Netrunner for what it is and are just starting on the early stuff I got. We are not aware of any trends or changes and it's like we have our own microcosm here.

My questions are: Have the rules changed seeing as a new core came out ages ago (I've heard a banlist exists now? A rotation?) ? Should I just stick with the pre-mumbad stuff/rules first to prevent confusion? And are any of the new cycles good and worth hunting down?

In my area, new Netrunner stuff have stopped coming. I only know a few packs but not complete sets and I think its very impossible for me to acquire Terminal Directive. So I don't know what to do concerning revealing new metas to our just starting circle of 4 people.