That sounds like a fun day in Amsterdam. One piece of advice: if your schedule starts to slip a bit, or if it's raining heavily, take the tram back from the museum. There's a tram stop right there, the routes are well-marked (most go to Centraal Station anyway), and you can buy your ticket on the tram.

The KLM lounge is upstairs. When you get to the end of the concourse, take the first stairs or elevator you see, and look for signs for airline lounges.