As to suggestions:
A riggers belt (with D-ring cut off) or Wilderness gun belt will work OK however a CR Speed belt will give you the most versatility in positioning your gear. California Competition Works or Progressive Machine and Tool Shell strippers (I prefer the x4s vs. the x6s) for your shotgun. You might consider a side saddle shell carrier if thats your thing (its not mine). For your AR you should be good with x1-2 Bladetech, Comp-tac or Ready Tactical mag pouches. Some like Redi-Mags on their rifle or couplers for their mags. You will need to experiment and see what works for you.
Good luck. Be prepared to constantly re-evaluate your gear while you're starting out.
Nick