Use them how You want, experiment with Your creativity and You'll get an idea on how to use them! =D And as for killing them, mines for mogura, and bombs for bug meister.
By bombs I assume you are talking about the cannon like objects? I am working on a new game right now and I want to use these enemies for a certain environment, but I want to make sure the proper fighting techniques are available for use haha.
So plant mines, and get the mogura to come up and detonate it, and shoot cannons into the sky at the bug meister?