No, the benefits are not included if you don't pay the destination fee. I imagine if I wanted to opt in they would let me though (Plat+ get a $10 voucher on top of the $30 F&B credit so it's theoretically a net benefit if you're actually going to use all the credits, but I'm not).

The lounge is open 24/7 but the evening offerings are only available Sunday-Thursday 5:30-7:30. Offerings outside food times are limited: water, chips/pretzels, Pepsi/Starry/Mountain Dew. I spent some time working in there last night. I asked to buy one of the bottled On the Rocks Manhattan cocktails (because the lobby bar was overrun with some group), and the lounge attendant set me up with a glass of ice, chips, etc., so I drank it in the lounge as I finished up work -- probably around 10:45pm. The attendant just happened to be there cleaning up and getting it ready for the morning. Very nice service.