What tools and stuff will I need to replace the chainrings on Hollowtech 2 cranks? – apart from the new chainrings!

Also for the chainrings – any opinions of the best ones – middleburn or stick with Shimano?

5mm allen key, little noggin tool to remove preload cap (or something that'll fit) Ideally a torque wrench for the l/h crank pinch bolts.
I prefer Shimano as they shift better IMO, but Middleburn last longer

Tools as above.
Deore steel rings weigh tiny bit more, but last lot longer.

The little tool to go on the back side of the chainring bolts can also prove mighty handy when the bolts just spin.

MIddleburn or Raceface rings over Shimano rings anyday

Not all chainring bolts need an allen key, some use T30 torqs, so check that first.