Best Sales Team Roles to Have?

We're in the process of restructuring our sales team and our strategy. We are a smaller company, we've really only ever had a few AE's and one CSM. But we are looking to hire an SDR role and want to continue to grow SDR's and AE's. Do you think having SDR's, AE's and CSM's are a MUST for a sales team? Or do you guys only have certain roles in your sales teams that make it beneficial?

To add onto this, if you have SDR's are your AE's still cold calling?

Thanks for any feedback!