I've done multi-week logging on the stratux, tried numerous power supplies, and even more numerous cables. With the old (long) SDR's, you get high heat and average power draws of 2.1 amps and peaks of as much as 2.5 amps. Be absolutely sure you get the power supply rated at 2.5 amps minimum. Now, even with a power supply that strong, a cheapo USB cable can lose enough amperage that the RPi will freak out. The best USB cables of all the ones I've tested are the "Amazon Basic's." They are solid, I think they're shielded, and they have no problem passing 2.8 amps continusouly (different project.) Plus, they are fairly cheap. With the last generation short SDR (radios) the average power draw hovered around 1.9-2.0 amps.
Be advised: if your red LED ever goes out when it shouldn't, then you're having power supply delivery problems from whatever cause. Do a normal shutdown of the RPi until you can get that problem corrected. There is a chance you will damage it and/or those expensive radios.
The USB bus spec is 0.5 amps, believe it or don't. So the RPi is asking for 5 times that much on occasion. That's why some of the phone/lighter adapters are not strong enough for stratux usage.
Always do a controlled shutdown of the Rpi, especially if you don't set it up as a read-only filesystem. It will bite you in the butt if you don't. Maybe not this time, maybe not next time, but it WILL happen. (Can you tell I've done a LOT of testing?) :) :)
On the reddit page, if you look on the right-hand side there are some links and if you can do the ".sh update" version, a lot of minor problems are handled for you in updating your SD card. SD cards have a finite write-life but it is in the hundreds of thousands, so I check mine about every 6 months whether they need it or not. :)
When you load a startux image to your SD card, reboot after it's finished, go into a terminal window and do a "df." If the file system size does not equal the SD card size (a mutiplier will need to be used from the readout and which multiplier depends upon how the card was formatted) If it is 4 Gb, for example, and you know your SD is a 16 Gb, then you need to resize it. Resizing if the file system is already resized can cause problems.
Re the 15 minutes wifi connect: my money is on power being too low. It is rarely even a minute after power-up that the wifi is not ready. At least, with the latest images.
Hope that helps. Skypuppy