Very common issues.
The bushings are a wear item. I have also seen them broken.
Carefully inspect all welds, especially around the heard area for any cracking or distorting. Good score on having two stingers. The 4" will likely be the one you'll need.
The spring bars are Reese round bars, IIRC. You can likely source some 1400# versions via craigslist locally.
The bearings are supposed to be lifetime. Some break them down and repack, some don't. I popped the caps and inspected for any water intrusion, and then replaced caps.
There is an "emergency kit" or something like that from Hensley that has all the consumables of grease fittings, pins, etc. I would also suggest a replacement ubolt kit for one side (just in case). Also, plan on an extra set of grease fittings. They are a wear item as well.
Check the strut bars and screw jacks for straightness.
The manual is available online if you didn't get one with the hitch.
The PP vs HA functionality is pretty much identical. Biggest advantage for the PP is the adjustable stinger, IMO.
Out of curiosity, how much did you score the HA for?
