Wow, you've really got some issues going on there. I've been a Stratux user since almost the beginning and here's what I would do in your case,
There are 3 main areas that cause flaky Stratux behavior: Power, Power, and Power.
What are the power requirements?
You can have the best power supply on the planet, but a marginal cord will cause voltage drop and power issues. You can have the best power cord in the world, but a marginal power supply will cause voltage drop and power issues. Here's the key to power issues: people think that because a charger or cord works fine with a phone/tablet, it should work fine with Stratux. But there's a key difference. The phone/tablet can fully charge over time with a trickle, but the Stratux needs 100% power NOW. When power is insufficient, the Pi will begin to shunt power to peripherals, such as the WIFI and USB ports. So the first thing to try is a new power supply and a new cable. I had a drawer full of USB cables at home, and the vast majority could not feed the Stratux. Also on the Stratux forums, several people have tested power supplies and very few of them are capable of supplying what they claim to be able to supply.
I have to re-image after power tests, is this a known fault?
Definitely not normal. It's almost as if your SD card is bad. The cards can get damaged during Stratux assembly if it's left in the Pi. Others have found teeny tiny cracks with a magnifier; I'd definitely try a new card.
My logs don't seem to have the lastest info
Logs are turned on and off via the web interface at 192.168.10.1. I don't use them so not sure but perhaps ifthey're not turned on in the web interface, and you're seeing old logs.
Can avionics interfere with UAT tower signals?
Yes it's possible, and the Pi can also interfere with avionics. I had undiagnosed Gremlins with my avionics when I tried velcroing my Stratux under the panel. The Gremlins went away when I moved the Stratux to the hatrack. Also, the 2nd most popular complaint with new Stratux builders is that "I'm not picking up any weather!". Unless you have a UAT tower in your front yard, you are most likely not going to receive weather until you are airborne and within line-of-sight of a tower. Also, go through all the tabs in the Stratux webpage and make sure everything is set the way you want it for the hardware you have.
Is long (15 minutes) wifi connect times indicative of anything?
Definitely not normal and another indication to me that something is catastrophically wrong with your setup.
In normal operation, with the latest version (1.2r2) it should take less than a minute for the Stratux to offer a WIFI signal. At this point both the red light and green light on the Pi should be/stay lit. The solid green light indicates that the Stratux booted up OK and is currently running. The solid red light indicates that there is sufficient power for the attached hardware.
I would try a new card, and flash the latest version to it. Here's some links:
http://stratux.me/
https://www.reddit.com/r/stratux/
https://stratuxadsb.slack.com/messages (you may have to create a free account)
https://github.com/cyoung/stratux/releases Get your full images here
http://updates.stratux.me/builds/ Get incremental updates here. Update via Stratux webpage; no "re-flash" needed