I think you've already figured this out but NET USE can only map to a share, not to a server with the shares as folders below it.

The C$/D$/E$ admin share is your only hope but then you have to dig out the specific share locations.

2>&1 just pipes stderr into stdout. That should come before the >>mount.log part which is why it's done - so that stderr goes into the log file.

The Crashplan example was right except for the redirection and logging part.