>what kind of politics is going on between the Lava-beasts?
Conflict between lava-beasts only occurs among those very far away, as the ones close to each other can hivemind better. Individual areas tend to want to propagate their own ideas as much as possible, and "idea wars" where two ideologies clash until one converts enough followers to emerge the victor, are common.
>We have floating islands?
Floating algal mats, some of them combined with rock-creatures from the surface. They grow thick enough along the equator to build on them, though large clusters of buildings aren't feasible; they have to be spread out.
The main servitor race of the lava-beast has spread to the four corners of Thumb, colonizing large swathes. They have long known how to harness electricity, it being a natural ability, but only recently have been able to use it to make machines. They did so more quickly than humans, however, as they were under the guidance of the Lava-mind.
You notice that the nearest planet, the one just slightly larger than Majora, has changed color recently, and you're not sure if this is a good thing or a bad thing...
Suddenly, a small group of ships comes from that direction! The Majorans, it seems, have barely survived our holocaust and have stationed ships in orbit to nuke our fair land! Luckily, they have only thus far hit the atmospheric cities and are bombing away indiscriminately otherwise, sparing the surface-colonies. They also don't suspect the existence of lava-beings. Satisfied that they have accomplished their mission, they land on Majora, exterminating the local populace.
The servitors are angry, and are turning to the lava-beings to guidance. The lava-beings consult the flows. What do you plan for them?
Also, everything on your planet is now immune to radiation, and also resist nukes to a much lesser degree.