If the e-bike is a Class 2 e-bike, then it should be okay to use wherever a regular bike is permitted.

Yes

I did not see any restrictions related to e-bikes. Depending on the weather some of the trails through the marsh areas may be a little too muddy for e-bikes. But there a plenty of dry trails regardless.

When we were there two years ago we used the bikes in the campground and on the road.

I don’t see why not; I’ve never seen signage not to. Seems to me it’d be a great place for eBikes.