Connecting all the cockpit controls can be a tedious work. Try the functionality by checking one function at the time. For the keyboard driving functions, I use Notepad to check the correct key action.
For making connections, the flat ribbon cable with matching connectors is very handy. (The types that are used for connecting Floppy-drives, Hard-drives and CD ROM to your PC main board) The connectors are available in various pin count size, from 10 to 40 pins. You can also get the fitting male pins (2.54mm pitch, they will fit perfectly on experiment board. You can use pre-assembled cable with connectors, but the loose parts can easily be assembled by yourself: The connectors have a top and bottom half, that need to be pressed together in a vise with the ribbon cable in between. Ribbon cable can be bought by the meter.
Building electronic circuits:
Since all circuits are basically one-piece projects, I normally dont bother making real circuit layouts. I use standard experiment board with 2.54mm pitch copper islands, and place the components in a logic fashion. Adjacent connections are done with solder, longer connections with 0.3mm f enamelled copper wire. (You can remove the isolation at the wire ends by heating them with your soldering iron for a few seconds). This method works quick, and the transformer wire isolation is good enough to avoid shorts over crossing wires.
I normally try to build with some ease for disassembly in mind. Modular building blocks help keep things organized and will make trouble shooting easier.
Using labels for various connections with polarities (i.e. supplies) will help avoiding wrong connections and possible damage. For the keyboard wiring connections you cannot do without clear labels.
The key to good electronics soldering:
Not too hot solder iron (40W or so), wipe the tip of the iron clean on a damp sponge after every solder point, solder quick, not more than 2sec (after that, the solder degrades). For soldering wires to connectors: First put a coat of tin on each end of the leads, then solder together.