Skype DNS Queries, MSN Messenger

I am seeing a lot of DNS queries on our network involving Skype, but to my knowledge no one in my home is using Skype. On several occasions there have been dozens of hits from domains like the following:

Also, there were 123 requests for this one: azscus1-client-s.gateway.messenger.live.com. Does this mean someone is using MSN messenger?

Finally, on our iMac, I see several days where there was well over 1GB uploaded - Can this be Time Machine back ups or large files (like video)?

Thanks.