welcome livingdead90
About the cracking coins - I have a nice collection of USSR coins and never encounter that kind of cracking, even on some pretty dented coins I have, cant break, or bend them for that matter. can you post a photo of a coin with a crack, before breaking it in half or bending it? What years are they?
About the silver coins - I don't have much experience with silver USSR coins, but I will try comparing it to some of my other USSR coins, what year are they?