I own the ET-733 and touching the probes to each other hasn't been an issue. I don't see how that could short out the electronics anyway but then I'm no electronics expert.
Yes, with any dual probe therm you could monitor the interior temp of your smoker if that's your goal. You just wouldn't have a probe to monitor the IT of the meat you're cooking. But, since you state you've chosen to use a Thermowand for that purpose, keep in mind that in order to check the IT on a regular basis you'll be opening your smoker door each time, and each time you'll lose both heat and smoke that will have to build up again.
When you lose heat our temp controller will have to kick in to replace the 20-50 degrees of temperature you lost depending on how long you left the door open. That's the whole point of a therm with dual probes: you leave one probe in the meat so you can leave the door closed until you're ready to foil the meat or perhaps flip it around or whatever.