I'm a C guru (been using C since 1978 when I worked on the Unix v6 kernel) and interested in helping out. I am currently self-employed (since 1985) developing embedded instrumentation, almost all of which is C with some assembly usually involved. I also have a number of Arduino's here, though all of my regular work is on custom system designs with volumes usually around 5000 to 10000 per year. I can provide appropriate references in the US (I work out of Oregon), too.
Oh... and I have experience with Lua (through game engine back-ends) and Javascript (though less with Javascript as I don't do that much web design work.)
I also have a complete electronics lab, three scopes (digital, analog, and MSO), GPIB controlled power supplies, 6.5 digit calibrated HP multimeter, signal generators, etc. My forte is embedded software but I'm fluent in analog and digital hardware design, as well.
Regardless of what you decide, I really like the way you posted the work. It sounds as though you've set this up for an enjoyable pace to get to know each other (without either side jumping off a cliff) and find out if the relationship is a mutual one. Which is exactly how it should be done. Nice.