A bunch of folks (many posting in this thread already) helped me. I had a couple of little issues - power cord, imaging the card, etc.
At the risk of a looooong post, here is all my collected wisdom. Note that I created virtually none of this - it's collected from many sources which I hopefully credited. And, here's a picture of the milk and homemade cookies my friend's wonderful wife brought us while we were soldering!
EAA's overview article - from September, so dated info:
http://www.eaa.org/en/eaa/aviation-...s/live-weather-and-traffic-for-less-than-$120
Very long 23-page forum discussion of the Stratux. Not organized:
http://www.pilotsofamerica.com/forum/showthread.php?t=85058
Short overview by the creator with additional links, including what we might want for GPS/AHRS connection info:
http://stratux.me/
12-minute video on physical assembly. Not needed.
https://www.youtube.com/watch?v=0rEOJrw4ds8
GitHub documentation. The stuff we really need is at the end and seems not to be completed.
https://github.com/ssokol/stratux/wiki/Stratux-Beginner's-Guide
Photo of GPS-AHRS connections attached. We need small wires. If you have little jumper things, we're in great shape! See also GPS-USB for the USB version which is apparently extremely fragile, and a truly ghetto enclosure.
Convoluted reddit discussion I have not reviewed:
https://www.reddit.com/r/stratux/
Info on imaging the disk.
https://www.raspberrypi.org/documentation/installation/installing-images/windows.md I ended up using SDFormatter on the disk and used Stratux V0.4r4. Release info here -
https://github.com/cyoung/stratux/releases
Questions/Issues:
1. Existing problem - eeee often added to the aircraft descriptions.
2. How to configure the AHRS with ForeFlight? (May be a ForeFlight code and/or license issue. I get AHRS on the Stratux web screen, but not with ForeFlight.)
Random notes -
1. The GPS has an internal battery charged by the whole system. It uses this battery to hold time/last location between reboots. Losing this charge means up to 45 mins for GPS lock due to Cold/Factory reboot.
2. Getting AHRS into the Stratux is technically/programmatically very difficult and Stratux is far from perfect. There is skepticism if the AHRS works correctly - 'not handling accelerated flight.'
https://www.reddit.com/r/stratux/comments/3w4kfg/foreflight_cuts_off_ahrs_in_75_ios_update/ (I am using ForeFlight 7.5)
https://www.reddit.com/r/stratux/comments/3w0od7/ry835ai_issues_anyone_else_seeing_this/
3. GPS must point forward. When you're looking at the GPS antenna and reading the writing on top of it, look closely at the top of the circuit board. There are 3 small chips along the edge. Notice the two on the right. One's the gyro and one's the compass. They each have axis symbols printed beside then. Basically, the writing on the GPS must point toward the front of the airplane.
4. Many have concerns about corrupting the Pi SD card via poweroffs. Here is an alternative:
https://www.reddit.com/r/stratux/comments/3qgccp/shutdown_button_solved/
5. To save space, we removed the cases on the SDRs and covered them in heavy-duty heat shrink wrap.
Enhancements:
1. Shorten antenna wires. This was well worth the effort - much neater.
2. High-quality power cable. Don't use a cheap one or it won't work.