No, it just takes a multi Reddit link that you paste, and for each subreddit, it will search for alternatives across the Fediverse.

You can select them one-by-one and subscribe to any you fancy.

No it's just a string of text: "https://old.reddit.com/r/subreddit1+subreddit2+subreddit3"

Nope. The multireddit link itself contains the subreddit names. All Voyager has to do is simple string parsing to get them.

No - you copy-paste a link that encodes the list of subreddits you were subscribed to, you could copy it from another machine entirely if you wanted