Can you walk with a stroller on these bike trails? How long is it to walk on the shortest trail?

Agreed. It would also be difficult for bikes to safely pass you.

Agree with Rick, it would be extremely difficult to navigate 75% of the trail with even the best of the jogging/trail strollers out there.

No. Even with a larger wheeled stroller (BOB) the trail would be very difficult to traverse. The shortest loop is approximately 2.5 miles and the largest is around 4.5 miles.