Does the ice bag need to be clean before use? If so, how?

I didn’t. You smash ice cubes in it, then remove them. I let the bag dry out on a rack. If it gets dirty, moldy, or smells bad, I will hand wash in warm soapy water, rinse thoroughly and air dry.

What surface do you use this on? My husband is concerned about damaging the countertop

Its easy to use ice crushers for home use and don’t worry it will not damage ur kitchen at all !!

Does this item work on all temperature ice?

Ive used it with ice out of the fridge and store bought ice. Worked great

How long will crushed ice stay frozen in this lewis bag?

Its not meant for storing the ice. Its more for keeping it all in one spot while you pound it with the hammer. It creates a very fine crushed ice the more you hammer it. My husband loves it make great mint juleps.

Is the ice crusher kit well made and durable for a frequent use ?

Yes, I have been happy with this set of bar tools.