Great to hear!
For the ladder upgrade: if you move upwards in the mine, you have to place a ladder under you so you have something to stand on and don't just float in the air. Without the ladder upgrade, whenever you place a ladder it takes 1 day extra day in addition to the normal time for moving and mining the square if needed. With the upgrade bought, placing ladders is free (doesn't take any additional time).
It's not a very useful upgrade, since moving upwards is rarely the best action to take. E.g. if you're trying to beat the hard challenge mode, you probably never want to move up.