I believe what you're looking at is the new, more fine-grained set of %Native_* resources you need to use native functions. Look for DP-423341 in the upgrade guide. It seems we failed to describe this requirement in the  Native API documentation (or at least I didn't find it where I expected it), so we'll get that addressed.

I'd also recommend defaulting to the new, dynamic upgrade guide that makes it easier to filter on particular types of issues. This is now replacing the old, static pages that were more reliant on / vulnerable to manual curation. In fact you'll no longer find those static pages from the menu in the 2025.1 doc.

Any tools that use SQL to access partitioned tables will just work, as from the SQL query perspective there is no change. This includes Adaptive Analytics, InterSystems Reports, and any third-party BI tools. Also, IRIS BI cubes can use partitioned tables as their source class.

We currently have no plans to support partitioning of IRIS BI cubes themselves, as they have their own bucketing structure and less commonly have both hot and cold data, so some of the motivations for table partitioning don't apply. 

yes, though the work to support applying updated mappings (as part of a MOVE PARTITION command) to all mirror members is still ongoing, so that's not something you can validate with the software currently published on the EAP portal.