If I use Launcher to start a userland app, must I first select it in Launcher, then select it again in the Hijack menu?

Yup. Userland apps can't "run" without calling Hijack's WAITMENU, which only returns after your app has been selected from the Hijack menu. In one of my Hijack wish threads, I suggested a new mechanism where Hijack replaces launcher's functionality and can give control to the app without having it call WAITMENU, but Mark's been busy.