the wild card is would be like anything.dreamhost.com - that covers all possibilties of subdomains of Dreamhost. So any of the DH servers can access the database, but no one else.
It's just like saying "Jokers are wild" when playing uno. That joker can represent any card you'd like it to represent.
And one per line just means that's how you seperate entries.
There could be some issues with the PHP version difference, but I don't really know anything about PHP. I'm sure there is some new feature support and command variables that will be suport and work on your system, and then you'll publish to DH and things won't work, or will work differently. One way around this would be to search the forum and the wiki and install php5 your self. It's been done before, and you should be able to find some helpful instructions.