#1
What is the best approach to really learn rockabilly? If you approach it fom a jazz standpoint, what specific techniques do I have to master? If you approach it from a country standpoint, how do you learn the picking? The reason I ask this is because today the thought occured to me that, people who are really good at rockabilly probably learned it through another style. If anybody out there plays rockabilly, can you explain how you learned it?
#2
Unfortunately there's not much interest for rockabilly on these boards... :/

I'm getting into rockabilly myself, but i'm a beginner too, so i don't know if i can help much.

Now that you mention it, i've been sort of trying to approach it from both sides as well. I have both the "Hot Licks" Video and the "Guitar Legendary Licks" Book+CD from Brian Setzer, and it's very interesting how he applies jazzy stuff (and music theory in general) in his music. For example in the video he explains how he uses chord substitutions to "jazz-up" simpler progressions and blues shuffles and make them more interesting. Lots of 9th, diminished, 6th, 7b5 chords and stuff like that. The book has a short section with the chords and scales he usually uses (in the gear section they even let you know what brand of pomade he uses, hahaha).

As for the country-side, my goal is to learn as many fingerpicking patterns/licks as possible, some chicken-picking, and typical country stuff in general (such as banjo rolls, country bends and turnarounds, etc.)
#3
I'm getting into the rockabilly as well but my gateway drug to it was actually delta blues kind of stuff.
But definitely what I think it takes to start learning it is study Jazz progressions and start getting into alternative chord patterns. It seems like Rockabilly is a lot of fast, country picking but throwing in Bebop Jazz scales.
Oh yeah make sure you acquaint yourself with the Bebop scale.

But for your question I listened to a lot of surf and blues before getting into Rockabilly.

Trying listening to the Cramps for some of that blues influence,
and I actually learned tremolo picking after listening to Dick Dale, the Surf guitarist
which helped me learn Commander Cody (that reminds me, "Hot Rod Lincoln" is a good start for practicing your speed picking)
And like carlosesteban mentioned anything that will teach Brian Setzer stuff will help you out.

Hope that helps someone

Everything Can Be Beaten
#4
If you asked most "Rockabilly" artists about "theory" they'd give you a blank stare..."It's just rock & roll, man!"
Trivia tidbit I read somewhere... On the original recording of Hot Rod Lincoln, the fast guitar part was artificially speeded up.... This led thousands of would-be guitarists to actually learn the lick in real time... Which is pretty cool.

I would suggest listening to the big names from the period. Most of this material is pretty simple from a structural standpoint... I would imagine 3 or at most 4 chord rock and blues figures played up-tempo.