Sorry, my mind wandered...
The gurgling stream wandered through the open meadow.
As a verb "The man wandered around aimlessly".
The stream wandered slowly around the meadow. Happily, I only wandered around the mall for about 40 minutes until I found you.
Deanie Etcetera's mind often wandered as she thought of her love, Mitch Longley. Jim Harrington wandered into Echelon Towers Voorhees to visit Carol Schultz.
Yes, "wandered" is the antecedent to the pronoun in the sentence. An antecedent is the noun to which a pronoun refers, and in this case, "wandered" is the verb that gives the action or context to the pronoun that follows.
I aimlessly wandered the streets.
The wanderer wandered in the dessert for many days.
The walkers had wandered into the deers' feeding ground.
cause: they wandered off the trail and become lost. effect: they had to be rescued.
I'm about 90% certain it is an adverb. About can serve as an adverb, preposition or adjective. I'm 99.9999999999999% certain it isn't an adjective as used here, but preposition or adverb depends on whether there is anything more to the sentence: He wandered about (aimlessly) => about is an adverb He wandered about the park => about is a preposition
Whiny Whitney wandered wildy while whining
The tramp walked down the street, begging for money as he wandered.
He wandered through the rabbit warren of interconnected hallways in the old hotel.