Howdy! Welcome (maybe) to Ghost!
I think the odds are pretty good that you’re going to want /some/ feature that needs the Creator level, like being able to load a custom theme. Maybe not, and certainly you could start at Basic and upgrade later.
Ghost has pretty good SEO out of the box, but unlike Yoast, it won’t tell you to make titles longer/shorter/whatever. But you could sign up for AHREFs or similar and get that sort of reporting (and the free tier is pretty good!).
Ghost Pro hosting includes sending email newsletters. (Pricing is based on number of members, not numbers of emails sent - for the daily newsletters, it’s a steal, especially.) Ghost doesn’t have an email drip (or other single-user emails) built in, although there are tutorials out there for setting that up with Zapier or similar.
You mentioned multiple newsletters. That’s definitely possible on Ghost, but check how many your hosting setup includes. Another option is one newsletter with member labels to segment who gets what.
Lots of people both publish their writing on their website AND send it out as an email. Ghost does both pretty seamlessly. When you publish, you can choose web only, web and email, or email only.
Ghost doesn’t have an email digest built in. (You mentioned sending multiple articles at once.) Some people who don’t want to send one article at a time send out a newsletter with links and excerpts/abstracts to their articles (assembled by hand or using bookmark cards). I’m also just finishing work for a client where I auto-generate her nightly newsletter email from everything published the previous day. That’s not built into Ghost, but I’m hoping to offer it as an add-on soon.
I’ve got an article (also sent in my newsletter!) about some differences between Ghost and WP here: Is Ghost the right choice?
There’s also the official ghost.org comparison: Ghost: The simple, powerful WordPress alternative (although I think there are a few spots where tradeoffs are presented as benefits…)