Seeking tech info on LX7007

I am trying to install an old LX7007 Pro IGC vario/computer in a 2-seat
glider. I bought a complete used package including the 2 units in front
and 2 in rear and all the cabling. But I am lacking some useful
information that I hope somebody here on RAS could help me with.

After this model was made, the company split into two, and I cannot find
any mention of this model on the web site of either company. No
manuals, no software, no data, no firmware, zip, nada - it's been
"canceled". If I was in the market for a new glide computer, that track
record would raise red flags for me. You can get all the support you
want for a Cambridge unit that is twice as old. But I got a deal on
this old one and I hope it will work for a while.

So here are some questions I couldn't crack from the info in the manuals
I have. Perhaps there is information online from the companies after
all, if so, please tell me where?

There are at least 4 serial (RS232) ports on the main unit, and that's
not counting the RS485 bus. "PC" (doubles as "Colibri/LX20"), "PDA",
"IGC" and "User". How do they differ in functionality? Which one
should I use to connect an e-reader running Tophat (based on XCsoar) if,
besides basic GPS location data flowing from he LX, I want functionality
such as uploading tasks from Tophat to the LX, and downloading flight
logs from the LX into the e-reader?

The "PDA" port (only) also has a 5V power supply line, to power a PDA.
How much current can be sourced from it? My Nook might draw as much as
half an amp. Is that safe for the LX?

There is very little info on the slave (rear seat) units in the main
manual. Does anybody have a manual specifically for the slave units?

In the system I got, the main unit is an LX7007 Pro IGC, and the slave
unit is an LX7000 Pro IGC. Are there incompatibilities between them?

The slave "analog" unit is fed an RS485 cable (power and data) from the
front-seat unit, and that then daisy chains to the slave digital unit.
But that latter cable is non-standard, DB9 to DB15. Anybody got the
wiring diagram for that cable? What extra functionality do those extra
pins add? In the cables I got there seems to be another "PC port"
dangling from it (the little round 5-pin connector).

The flight logs from the LX7007 are written to its SD card as .LXN
files, not .IGC. (So much for standards!) SeeYou can convert those,
but then they are no longer "IGC secure" (for badges and records). I
have seen mentioned somewhere that later versions of the LX7007 firmware
switched to .IGC files. Is that correct? Which version of the firmware
does that, and how can I get it? If I can't get that, can I send the
..LXN files to the SSA badge dude?

Can anybody send me a copy of the "LXe" PC software that originally came
with the LX? Are versions of this software and versions of the hardware
forwards and backwards compatible? Is it worth having?

The airports and airspace databases need updates over time to stay
accurate. Have there been updates? How can I get something newer than
what's stored in it now? If I can't, can I override the old info for
specific airports with info I manually put into my turnpoints file?

Thanks for any info.