Black gold sights have the best pins, Spot Hogg are probably the toughest. I’d recommend a multi pin slider. You can have the regular 20-30-40 etc for hunting and then dial for the long bomb practicing. Make sure you get something with 3-axis adjustment if you are shooting anything other than flat ground.
whisker biscuits are simple but you will lose some arrow speed.
Hamskea probably makes the best drop away rests.
Buy the accessories used off Rokslide or Archery Talk, there’s always guys upgrading.
I can’t help you on stabilizers, you probably need one or two but I made my own. They seem pretty expensive for what they are.