It is still in the process of being moved. Please see MartinM's post in this thread:
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[Voip.ms] Server Status Suggestion(s)To answer your second question, try pinging the various servers and see which one has the best results for your physical location.
Pinging is a place to start and then I would suggest actually trying any server you choose for a while to see how it performs for you. Loading, number of hops to it and updates or course will have their effects on any particular server you might choose.