Salem

After breaking a black tile softened by a pile of wood there is a chance to go down to next level of mine...

Can you have mine supports to stop cave-ins from failed attempts and still have a chance to go down to the next level or do I have to run the risk of getting cave-ins for the chance to go down a level in a mine?

one does not affect the other. don't fear that setting a mine supports will lower your chance to get a cave down.

The only factors required for a cave down is. X amount of mined tiles that is divided by time spent at that level to the best of my knowledge. (i'm at lvl 8 with no intentions to go further down)