The firmware updates simply came from the community, I had little hand in those. The pause works, but it needs to wait for the buffer to be empty, during infill this can take a while.
The feeder nor the hotend changed, so any extrusion priming problems you might be experiencing, I don't think they came from the heated bed upgrade. Might just be an unlucky timing for a partial nozzle block?
No idea why there is an endstop in the kit...
The bed comes with a significant improvement in bed stability, so you most likely never have to adjust it again, unlike the wooden bed you had before.
Printing with a heated bed can be a bit tricky, I leave it to the above comments for assistance there. (I'm still a blue-tape guy myself)