canDeployWeapon [unit, onGround, returnPosition]
isWeaponDeployed [unit, onGround, returnPosition]

Parameters:
returnPosition: Boolean - (Optional) Default false. true to return weapon deployment position on the surface of the object or ground.

Return Value:
I'm not sure what info is already easily available, but in order of preference:

1. Array of intersection data like in lineIntersectsSurfaces,

[intersectPosASL, surfaceNormal, intersectObj, parentObject, selectionNames, pathToBisurf]

2. Array - format PositionASL