How to set up a test site?

[Outbackmark]

You can do that, the TOS states you may have a test forum but it must be behind a "grey box" login.
You would have to access the forum on server B by IP or server name as http access will still be pointing to forum A.
I have done exactly this when moving large boards from one server to another. It may be worth checking but some server managements offer a move service and do it all via SSL direct from server to server, this is by far the easiest way as with the original method suggested you would still have to upload the latest DB backup to get everything up to date. Not too hard with a small DB but if the compressed DB is over 30 megs I would suggest you get the server techs to do it.