Let me start by stating the only word order rule that applies to the German language:
You can move almost any part of the sentence to almost anywhere, as long as the verb is second (or last in subordinate clauses).
With that: Yes, den Toren is the accusative of der Tor and that is used as the fool. Die Reisewut is, however, not an object (den Toren is already accusative), so it should be subject. It's hard to see, because accusative and nominative cases fall together for feminine nouns. It's easier if I substitute for a masculine noun:
Den Toren packt der Reisetrieb.
I'm inclined to say that there be no verb in German that has two accusative objects, but I'm sure that Emanuel will show up and give me a counter-example if I did so.
The word Wut, while nowadays only meaning rage, anger, has preserved its older meaning in compositions where it is understood to mean insanity or possessed by. Somebody who is reisewütig is possessed by the will to travel.
Apparantly, this word is connected to a Proto-Indo-European root *wāt- meaning prophet.
I'm not entirely sure about the true meaning (I never am with proverbs) but your meaning is certainly suggested. I'm pretty sure that being a proverb, it can also mean something along the lines of the fool thinks that the grass is greener on the other side, the wise man knows it isn't, or maybe merely the fool wants to see the world, the wise man already has?
 See this question (in German) in case you thought that every German sentence had a subject. But it's still safe to assume a subject for sentences in the indicative mood and the active voice.