These are my personal fit notes:

I did the neck ribbing with a US 2. (In the testers’ results the neck tended to stretch kind of wide.

I cast on with CC2, then 2 rounds of CC2 ribbing; 3 rounds of CC1 ribbing, 4 rounds of MC ribbing.

I got gauge using a US 5 needle after blocking.

Worked sweater as in pattern except I didn’t add neck short rows.

For body hem, I did 2 rounds of pink (CC2) and 2 rounds of orange (CC1) in stockinette using US 4, then did a 2x2 rib in MC for a bit using US 2, and bound off with a simple purl bindoff with US 4.

For sleeves, I knit 19 rounds in MC using US 4, then did the 1x1 colorwork for 2 rounds in US 5, did 1 round of MC in US 2 stockinette before 3 rounds of 1x1 rib, making sure the knit part of the rib was even with the pink color. Bound off with basic purls using US 4.