Takes about 90 minutes with some breaks for photos (one way from the start to the end). We usually walk back on the Cliff Walk itself but many people prefer walking the street.

There are benches and seats but I don’t recall seeing any tables or really open areas for a picnic. There are small small beaches but they are gravelly and filled with pebbles so it may not be very comfortable if you intend to lay out a picnic cloth and enjoy your food. If you buy tickets to the mansions however, they should allow you to have a picnic on their grounds. I saw people doing this at the Marble House gardens.

The end opposite First beach

Not really. There are so many steps up and down throughout the walk that you would be picking up your stroller continually. Most people with young children will have backpacks to make the Cliff Walk. That seems to work the best for everybody. I have seen a few strollers and they struggled the whole way.

Early morning almost any day.

There are trolleys and public restrooms. Just need to wear masks

We parked near Easton's Beach on Memorial Dr and started at that end of the walk. When we finished at the other end, there was a convenient shuttle to take us back to the parking lot.

I apologize but am unable to answer your question generally. A large part of the walk consists of a concrete surface, but you’d have to check the rules. However, the areas of the the path that consist of rocks are unsuitable for a scooter.