Ok, so is a wanderer a gadabout or a gaddabout? Is that (the about) why it's gaddative and not gadditive?
From Atomica:
gad1 (găd)
intr.v., gad·ded, gad·ding, gads.
To move about restlessly and with little purpose. See synonyms at wander.

[Middle English gadden, to hurry.]

gad'der n.

gad2 (găd)
n.
A pointed tool, such as a spike or chisel, used for breaking rock or ore.
A goad, as for prodding cattle.
tr.v., gad·ded, gad·ding, gads.
To break up (ore, for example) with a gad.

[Middle English, from Old Norse gaddr.]

I was intrigued by the transitive and intrans. requirements. I can hardly restrain myself from adding 'about', but I guess you could say, "He gads", meaning that he gets around a lot. You'd have to say, "He gads goats (or ore) for a living".