Yes - you're able to save data behind a login using the point and click functionality as it extracts whatever data is loaded in your browser ("local scraping").

And no - if you choose to also create a cloud recipe that runs on the server, the remote browser instance won't be able to access data behind a login.

It's possible but I'd rather not store third-party credentials for the time being.

It doesn't look like it. I got an error trying to scrape my HN upvotes url.