Westbound trains, for the most part, platform on Tracks 1, 2, and 3 at Jamaica. The train that takes you from Huntington to Jamaica does not stop at Woodside. The conductor on your train will tell you on which track the train to Woodside will arrive. The Woodside train MAY not be a direct connection, but may arrive 5 minutes or so after you arrive in Jamaica. (You get off your train at Jamaica and wait 5 minutes). And one more thing... it may not be the FIRST train that arrives after you in Jamaica. The signs on each platform will scroll a list of stations that the next train will stop at. Just make sure the train you board stops at Woodside.
The train to Woodside will stop at Platform B. Conveniently, the train to Mets-Willets Point also leaves from Platform B, but will be heading in the opposite direction (as you are going West to go to Woodside then back east to get to Mets / Willets Point). You wait there for the train to Port Washington. Just follow the other Mets fans. You won't be alone.
One note... They will not hold the Port Washington Train. Therefore, if your train is late getting to Woodside, and the next train isn't for a half hour or so, you might as well just take the 7.
And yes, I'd take the 7 train to Woodside after the game. I wouldn't want to miss my eastbound train because I had to wait for a westbound train at Mets / Willets Point. Remember, trains from Woodside to Jamaica (and other points east NOT on the Port Washington Branch) leave from Platform A.
You may simply want to buy a round trip ticket from Huntington to Woodside, and ride the 7 train from Woodside to CitiField. Your return trip in the PM (if it is indeed at 5:58 PM) will be a PEAK ticket. You can always buy an off-peak Round Trip and pay the step up fare onboard the train w/o paying the fee on your way home.
I meant to respond to this last night, but forgot. Anyway, thanks a lot for the info. This was very helpful getting to and from the game today.