A couple of thoughts on this:

1. I don’t think it’s possible to follow Mastodon accounts through Lemmy - at least not yet. To be honest, though, after playing with their interoperability, in my opinion it’s best to just set up a Mastodon account and use it as a separate platform. The formats are different enough that you’ll be grateful for the more Twitter-like UI experience.

2. I’m personally not big on messaging actors or other series personnel without a very specific reason. These are personal social media accounts, and not everyone appreciates extra “noise” in their feed. Those who are interested will likely find out about us organically, and we would always reach out if the timing seemed right and we thought they would be receptive.