Is the actual battle site walking distance from the museum? Thank you

It depends on what "walking distance" means. It would be a pretty good hike from one area to another. You really need to drive from place to place.

Define walking distance. You could probably walk 20 miles.

Agreed, the entire battle was three days over a large span. You could hike it but driving to each site is ideal to see everything. I highly recommend a audio tour as well.

Take your car but I suggest you get the self tour cd. It tells you where to stop and what happened in that location.

Not all of it the battle ground is but there's other parts to explore