Hi Andrew,
1. Is the module CSS styling friendly, or am I going to need to hack php files to get a specific look? Specifically, I'm trying to get something like this.
The module is CSS friendly, but if you want to achieve something like the site in your link you could also use a article and load the module there with {loadposition CMCMODULEPOSITION}. The advantage of this is, that you could mostly use the WYSIWYG-Editor of Joomla.
We tried to minimize the CSS in the module, so you can use your own Joomla template css code to customize the layout (starting with .cmc-signup).
2. Does syncing take place automatically, or do I need to go in and do it manually on a regular basis?
After you installed the extension, you set up the Web-hooks (in Mailchimp and Joomla) and do a first manually synchronisation. After this you normally don't have to do a manual resync again, because any changes are forwarded through the Web-hooks.
Best regards,
Yves