OK. So I've set up a new site on Acquia dev - pulled down the code to a local vhost - and pulled down a DB dump and loaded it into my local DB copy.
What should I do now to make things work nicely. Here are some very brief notes:
1. Use the example.gitignore file.
2. Uncomment the lines in settings.php, copy example.settngs.local.php to settings.local.php and put the DB connections in there.
3. Add a value to the HASH config in settings.php - I used $HASH_SALT
4. Set up the vcs config value in settings.php - this is what worked for me when pasted at the end of settings.php:
$config_directories = array(
CONFIG_SYNC_DIRECTORY => $app_root . '/../config/sync',
'vcs' => $app_root . '/../config/' . basename($site_path)
);5. Remove 'vendor' from .gitignore.
This will help with running drush commands if you install drupal console on your local dev copy.