Hi Bob! Welcome to the club! You're in the right place!
Your questions are pretty common with these smokers. First, let me recommend that you not "chase" temperatures. If you set the dial to 225, the analog controller (stock) will have temp swings around 15-20°. This is totally normal, and the overall temp will average to what you have it set at. Nature of the beast. My advice is to not even worry about box temp (I never do with my #1). Set your temp and trust that your smoker is doing its thing. If the results aren't as they should be, then start checking to see if there is a problem. For example, if you smoke baby back ribs at 235° for 5 hours, and they are nowhere near done, or WAY overdone, start checking. What you will find is that the results will be consistent with the set temp. That's the beauty of "Lazy Q;" unlike "traditional" smokers, you really DON'T need to monitor your box temp constantly.
As for the Auber questions: First, let me say that the Auber PID is a fantastic accessory, but is absolutely NOT required to produce some really good Q in these smokers! I used my #1 for almost a year before going to the PID, and never had a bad smoke!
Your question about the probes concerns the box temp probe. There are two kinds - a removable probe, that you drop down through the top hole and attach to a shelf, and a wall-mount probe, that you permanently install in the back wall of the smoker (requires drilling a hole). The wall-mount probe is not required, but is a great way to go, if you can handle the install. Either will work. And yes, you drop both probes (meat and box) through the top hole, and plug your smoker into the Auber. It then controls the element, based on the readings it is getting from the probes.
So, bottom line: Do a few more smokes by monitoring the internal temp of the meat with your Maverick, and don't worry about box temp. Your life will be much more "stress-free." Then, if you really want to have that super-tight accuracy, get the Auber. Either way, you'll end up with some really fine Q!