Before the shooting at Mikes house in part 2. Mike is always talking about his important business with roth and nobody can ruin it. What was this business and why was it so important?

Was it a stepping stone to go legit (unlikely but you never know).

Or buying the casinos in Havana to go bigger and more global (another greedy scheme).

Did he fully trust Roth before the shooting or was he suspicous of him before? as Frankie was complaining about Roth and the Rosoto Brothers.