In SC 3.3.0 there are community plugins for SME and SMSQL. These plugins are not supported by NGS and are only obtainable through NetApp PS. If you are interested contact your sales rep.
In SC 3.4.0 the SME and SMSQL plugins will be built-in and supported.
These plugins are for interfacing with SME and SMSQL, so Snap Creator can run those backups through powershell cmd calls. In addition SC can snapvault the snapshots since the PM integration isn't always possible we wanted to provide another option to doing things.
As for SMVI SC could certainly trigger backups for it too using CLI but there is no integration plugin
You can basically turn everything off in SC so that it simply runs remote CLI calls through it's agent, this would suffice for a single pane of glass scheduling for Snap Manager's. Some customers are certainly using it in this way.
There is no beta being done that I know of for 3.4.0. It releases as mentioned end of June. There will be many features in 3.4.0 not just SME/SMSQL and we will announce them on community when they are all confirmed.