1 & 2
FreeEntity whicheverbubble.bubble\entity, after which Delete whicheverbubble.bubble... you have to free the mesh that's assigned to *whichever* instance of your bubble type before you delete the instance itself. FreeEntity for meshes, Delete for instances of a type.
3
I would place a pivot at the exhaust of each car which acts as a generator. When you create a new instance of your bubble type you reference the global position of the car in question's generator pivot and place the new bubble's mesh there.
EDIT: Ross types faster than me, pun intended. ;)
FreeEntity whicheverbubble.bubble\entity, after which Delete whicheverbubble.bubble... you have to free the mesh that's assigned to *whichever* instance of your bubble type before you delete the instance itself. FreeEntity for meshes, Delete for instances of a type.
3
I would place a pivot at the exhaust of each car which acts as a generator. When you create a new instance of your bubble type you reference the global position of the car in question's generator pivot and place the new bubble's mesh there.
EDIT: Ross types faster than me, pun intended. ;)