Ben, you are going to love the dummy, although it looks huge it’s actually quite nimble. I did my Jogle on mine
I ran mine with a rohloff, hub gears are idea on a cargo bike, especially with kids on the back. Being in the wrong gear following an unplanned stop can be a challenge when carrying all the shopping plus offspring. For the older kids fitting a stoker bar is a good idea, it gives them much more confidence and makes the whole bicycle more stable. Another great accessory are the plug in running boards, I had a set, they plug into the horizontal tubes and keep little feet happy, they also help when supporting silly loads.
You will also want an assortment of straps etc fit when you come across random tables etc which need strapping on the back.
Plenty of ideas here
https://www.xtracycle.com/product-category/components/
One expensive but vital addition is a double legged centre stand, if the children are small enough to need strapping into seats a stable platform makes life a lot easier and safer.
As you might be able to tell I miss mine a lot, it’s a real life changer. We were car free for a few years and it delivered two (occasionally three!) kids to school, did all the shopping runs quicker and tess stressfully than a car, towed other bicycles, collected three full sized hay bales, a fire place, logs, coal and was generally the most useful and fun bike I’ve ever owned. Mine lived in our hall, when I finally build my man shed I want a bigfat dummy running 29” wheels.
If you want any dummy life advice just ask.
We’re all individuals, except me.
I woke up this morning but I’m still in the dark
Must admit being a child of the 90's I was very tempted by the bright purple version 
. The whole "I'm just driving round the corner to the shop to buy some milk" stupidity is soooooo last century.
