I just want to ask a simple question, Are only premium members allowed to take vacations with certain players? I thought Vs would apply to ALL games being played but I found an opponent who did it with only a few of us...

any player can take vacation time as long as he/she has days remaining. 

You will find that the game status of "Waiting" changes to "Vacation" once the player's opponent makes a move.

well, that really doesn't clarify anything...  what I'm not sure about is, can you take vacation time with a partial group of matches being played?  doesn't vacation time apply to ALL the matches???  Is it a premium members only priviledge?

It might be something where his vacation time kicked on automatically, but it won't kick in on certain games until it's his move, where the other games were his move so it kicked in on those initially.

1 - can you take vacation time with a partial group of matches being played?

No. Vacation applies to all matches.

2 - doesn't vacation time apply to ALL the matches??? 

Vacation time applies to ALL the matches.

3 -Is it a premium members only priviledge?

Vacation is the same for all members.

If you think someone is playing while on vacation it is possible they came back, played a few games and then went back on vacation. This is easy to do with auto-timeout protection.

vacation is NOT the same for all members. premium members have auto-vacation. so while they can't intentionally go on vacation when it is their move, vacation will kick in when they have about 90 minutes left in their game.