Volumetric spawn conditions, healing, and special explosion damage for a monster

Hello, I just discovered this program today while looking for a way to create a custom monster for when Caves and Cliffs Part 2 comes around. I'm calling it the "Molten Golem", and I'm not sure how to give it all the features I want. The idea is that it would spawn in lava pools that have a 3x3x3 volume with a volume of at least 3x3x1 of air above it (It's a large mob.), spawning at a certain depth range, capable of healing itself in lava, and capable of throwing an item (or firing firecharges) that can destroy most blocks but not all, with the exceptions being what I consider "fire hardened" blocks, consisting of metals, diamond, and most Nether blocks. It also recieves extra damage from water, be it by flow, source, or thrown bottle, as well as by trident and axolotls.

The general concept of it is to have a deep-level mob that is stronger than an iron golem, but probably weaker than a Warden, that forces some underground defensive base building and experimentation with ways to combat it.

As of yet I have given it a model and texture, and will work on sounds later, but have given it a basic AI that avoids water and will break cobble and obsidian (mainly with the intent that it would open up more areas for its kind to spawn), and will of course do the default attacking, as well as damage players who touch it. I also can make it spawn in lava, but haven't tested it yet so I don't know if it will spawn in areas too small and suffocate.

Am I trying to ask the program to do more than it's capable of, or are these relatively feasible once I have spent more time with MCreator? Also, for reference I am a java player, and am using the Forge-compatable project option.