Playbooks...

Is there a way to edit them into the teams so that I don't have to set them for both teams whenever I start to play?

Or is there no way to change the default plays for teams?

You can modify the default players by editing the appropriate fields in teams.dbf (see the Teams.dbf Editing Guide in the NBA Live 07 section) and referring to plays.dbf for the ID numbers for the specific plays.