Thanks so much for playing BraveKing!
Couldn't figure out how to build rooms because I accidentally pressed to skip the tutorial.
Once you mine open enough space in the home world, you just need to click the build button and find the room option.
Also kept collecting eggs but not sure how to use them?
This was actually a bug that should now be addressed in 0.85.26 (the bug reduced the reward pool to mostly companion eggs). These are companion eggs that can be used later in the game.
Something I didn't like so much, "spend skill point for 5% chance to trigger cool effect." It's a bit hard to be excited about such low odds.
Understandable, as you progress you might start to get an idea why the odds start off this low for some options. There are several different mechanics that contribute to effect outcomes in battle. These chances culminate in to quite a lot of activity as you progress. Companions, equipment, orbs, etc. can all trigger different effects. If the chances were too high, then the visual clarity of battles would be overloaded with effects that are proccing several times per turn.
There is also a tier system that allows these chances to improve (later in the game).