Vinnie,
1) no limit that I know of.
2) yes, a Masters player can play for a CAT team in the
VMSL—even U-21 as they are allowed overage players. Going the other way you, if you are signed with a
VMSL (open division) CAT team, you must be at least 35 to play Masters: you must be signed with the CAT Masters team if you are one of the three underage (31-34 year-old) players.
Of course for a few teams like ours I don't think we have anyone under 40 so the whole issue is moot.
Hope this has been helpful, Peter