Insulating layers question

Yes, basically take it slowly, rehydrate and don't wait to layer/delayer. ;)

Usually I don't layer up to the point of being cozy at the start of my hike/climb, because I know I'll start sweating in 10 minutes. I can endure a bit of discomfort for a short time.

have you considered the Patagonia Nano Puff as a mid layer ?
It could also double as a light outer layer during warm periods.
very light weight, yet warm for its weight, not bulky, and highly wind resistant.
yes, extra $$$ if you don't already own one.