how self-contained are the mechanics?

Particularly, the new lockpicking, hacking, and haggling features? Which files should I look at were I wanting to port those to, say, an UP+ version of the game?

Just about every map, hackfile, and python script...

Well, let's break it into pieces... What files are related to the online banking? One would think that maps are not concerned unless new computer habe been added, and not every script affect it, right?

For the computers, every hackfile and at least all the levelscripts for maps with a haven. Not sure if modifications to the haven maps or vamputil are necessary.

For the pickable boxes you have to edit the maps.

Haggling involves changes in the dialog files mostly.

I just responded to a post you made regarding a similar question.

https://camarillaedition.darkbb.com/t2201p15-mechanics-charts#42831

Read that and we can talk about what you need if you're looking to chart it all out.