Yes, you can get around quite well with a walker.
Yes however you will most likely not be able to make it down into the waterfall part, it is concrete slab stairs with no rails and are often wet
A walker can be used in most of the Gardens area. However there are some areas that cannot be reached by someone that can't go up and down stairs easily.
Yes, park is well laid out
Yes I even saw several people having a picnic
Yes
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