What do faculty members mean when they say "happy to find a time some time to chat more about it..."?
The "just let me know part" invites you to let them know your preferred times and propose a way to have a chat.

The typical medium to let them know would be via email. And then the typical medium to chat would be in person. But that's it's not so important. You've been invited to make a suggestion without much advice. So any response that is both reasonable and polite should work. Even if the professor will "counter" your suggestion with an alternative.