I am new to RC. I bought a Duratrax Evader BX for my son and have read many differing opinions on break in and set up. Any advice for a complete newbie on how to best break in and adjust.

This is an electric buggy. There is no break in involved.
Put your batteries in and go. That is why they call it ready to run.
Adjusting it is a different thing. If you hear the gearbox squack after it has run a while you may need to adjust your differential. OR if you pull the throttle and the car does not move right away you may need to adjust your slipper clutch.
Check your manual for instructions on how to properly do this.
If the vehicle drifts to the left or the right, You will need to adjust your steering trim. That is done on the radio.
That is about it for basic adjustments.
Go out and have fun!!

One point of caution, the servos in Duratrax are sometimes easily broken. Try to avoid any hard front end hits. If you find this to be an issue replace with a better quality servo or beef up the servo saver. Still not a real expensive fix.

One point of caution, the servos in Duratrax are sometimes easily broken. Try to avoid any hard front end hits. If you find this to be an issue replace with a better quality servo or beef up the servo saver. Still not a real expensive fix.

Like the JR 590Z inexpensive metal gear servo.