Frap1K Glad to see it's starting to take shape, nice looking game so far!
But remember, any objects in a container can't be destroyed unless you are also okay with everything else in the container being destroyed too. Try changing it so that the objects you don't want anymore are "Set Visible" set to "Invisible" and disable collisions (don't know that one from memory though).
Also, the healthbars being offset comes down to image hotspots, as the math for positioning the healtbar assumes it has a hotspot in its center.
As for issue #2, try adding a variable to the zombie like "alive" and have it start as 1, then in event 41 add the condition to check if alive = 1. Then you can set alive to 0 in the actions for it so it never triggers again after the first trigger
And anytime! I'm really glad to help