So here's my experience living about 5min away from the trail.
The north section from Milford Beach (206) to 739 is going to be on-off road. You can ride from the beach down to Raymondskill, but then you take 209 up to Zimmerman Rd (dirt road on right) which loops back to 209. *This avoids illegally riding on the portion where Eagles are known to nest.* Then ride 209 for another 300 feet and make a right onto dirt Zimmerman Farm Rd. This is closed off to vehicles and a nice ride that will loop you back onto 209, skipping yet another hike a bike section of the Mcdade trail. Then cross 209, hop over the guard rail and you are back on the rideable Mcdade. One of the nicer sections too. You'll eventually climb out near the road and you can either ride 209 to the traffic light or hike the bike up a few stupidly steep hills on the Mcdade. Whoever builds these trails in the park needs to reevaluate career choices.
South of 739 to Bushkill Falls Rd is pretty much all flat fields and where you will find a river campsite. I can give you that location if you want. There is a general store near 739 at Dingmans Campground for refreshments. There is a deli with some good food and picnic tables at the 209 and Bushkill Falls Rd intersection. That's the last food stop until Shawnee.
South of Bushkill Falls Rd to Shawnee is mostly up and down. There are a few fields mixed in, but also a couple super steep hills. The area around park headquarters going south is probably the nicest area of the whole trail. And when you finish the trail, keep riding to whatever the restaurant in Shawnee is called.
Also, the surface is rough gravel. Nothing like the cinder used on rail trails. I thought I was going to ride my gravel bike on it, but for longer distance, my back and sit bones won't allow it.
Also, it's a National Recreation Area.