Go up to the street level and walk outside. The Duck Boat ride is stationed in front of Union Station (front being side facing toward Capitol building).

Every 60 or 90 minutes I believe.

I have not done the Monuments Tour, but I do know that we viewed the few monuments from an angle that you can't see from a car or by foot. The Ducks tour was by far the most fun and enjoyable tour I think I have ever taken! I thought we would just cross the Potomac River and get to the other side and that woud be it, but golly--we were in the water for at least 20 min touring around and looking at things. Don't miss this opprotunity to ride a real 70 plus year old Army vehicle!

Yes, the tour is 90 minutes.

The steps are re a little steep but they are closely spaced. There are handrails you can hold onto and the boat captain will help you get on board. I have difficulty climbing steps also and it was pretty easy. There is no rush to get on board the duck.

I don't believe so. it takes you on the back side of the Pentagon and next to the approach runway for Reagan Airport in the Potomac but not National Harbor.

It would be better to reserve tickets on line. It will save a few dollars and you will be assured of a seat at your desired time

No, the duck is a accessible only by a set of stairs (it is a WWII landing craft).

The Duck is only accessible by a set of stairs (it is a WWII landing craft) so I don't think that strollers could get on board (if you intend to push the children in the strollers into the boat). If the strollers cold up and you can carry the children and the strollers on board then perhaps it could be done. Not sure.