Let me ask ...
Why?
Why throw parts at a problem?
Why ask for advice & then ignore it?
Why use a Chilton's manual, when you have access to the 96 Tracker factory manuals?
Now let me answer your questions...
By DTR, I'm assuming you're referring to diagnostic codes, no, those are unlikely to be related to a lighting issue, not on a 96.
No, no car is ever wired like a christmas tree, and the Tracker is no exception - the lights are parallel circuits, when one light goes out, the other stay on.
You didn't ask this as a question, but, no, it's unlikely to be a ground issue, the affected lights do not share a common ground, they do however share a common power source, and control switch - it is possible however that you have more than one ground issue.
Why not get a voltmeter (if you don't have one, buy one, even a Harbor Freight cheapie will serve the purpose - it'll actually be less expensive that the new switch assembly) and troubleshoot the problem - the Tracker FSM (Ack's FAQ) has step by step instructions.