Items to make a cave, which biom

In which biom I can find large leaves and large rocks so I can make a cave for a hospital? Also is it true that for the first 3 days of playing my wolves won't be sick?

Den items can be found in all biomes, it's just a matter of luck!

And yes, for your first 5 rollover you are immune from illnesses. On your 4th rollover the herbalist quest will unlock

Ok thank you! :D