Thanks for the reply!
1. Ahh, rookie mistake. I've changed it to ResourceLocation(modID, "entity_name") now.
2. Great.
3. I have not implemented my own features yet, but there are some features I plan on implementing into the falling block.
4. I tried using the hasTileEntity and createTileEntity methods (even checked with @Override and there were no errors), but that crashed my Minecraft.
5. Another rookie mistake. BlockDungeon is gone!
6. I was expecting it to be something like that. I've fixed it using a boolean to determine what type of "Push Block" the entity is. That seems to work well. (My custom entity can only be a push block anyway, I know it's not the best solution, but I had lots of trouble with networking in the past so yeah.)