For 'remains stationary' under the chameleoline cloak's entry - does it mean holding perfectly still (i.e. not taking physical actions) or just standing in one place (not taking move actions)?

Mhh, I'd say neither, exactly.

"No big, obvious movements" would be my preferred interpretation: No Move actions, obviously, but also no throwing grenades or reloading a missile launcher. Firing a gun might give away your general position, but you'd still count as remaining stationary.

Though the reading closest to the actual wording is simply "No Move Actions".

I would say that it means "no Move Actions", although like Myrion says, there's a fair bit of interpretation that could go into this.

Remaining stationary simply means that you are not moving around, you are remaining stationary, standing in the same spot. If you have a Cameoline Cloak, I'd say that you can reload a missile launcher (provided it's small enough to be loaded by you alone, or you and another person also wearing a Cameoline Cloak. I'd say that you'd definitely be able to fire your weapon, provided you are lying down or are crouched, or otherwise don't move between standing/prone/squatting position, etc.

If you are wearing Cameoline Coating, I'd be a bit more restrictive, since you can't angle it the same way as Cameoline Cloaks, to cover yourself while doing reloads standing, etc.

But in a nutshell, no movement actions.

Right, with the chameleoline cloak you can hold it like a sort of tent... I was thinking of reloading your missile launcher while wearing a poncho, which would leave your arms and the missile launcher pretty exposed.

I concur with fgdsfg now.