I've grown and successfully processed it myself. I just scatter the seed by hand, but aim for about 1 seed per square inch. That density has worked well for me. I still go in and hand weed it (I grow it in rows that are about 2' wide, so that makes it easier).
Once you see it start to yellow it's time to pull it (don't cut it or you're losing the fibers in the roots). Pulling by hand is easy.
Then I do one of two things -- either water retting for about a week or two (will vary a lot depending upon temperatures, bacteria, etc in the water, so you'll want to check to see if the fibers are showing when you blast it with a hose) or "dew retting" where you let it lie outside and rot slowly with the dew. I try to flip it every so often so that it rets evenly... but have not had the best of luck with this method. After a month outside it still didn't process as nicely as the water retted flax for me.
I built a german style flax brake for the initial processing, and then found an original antique hackle (basically a bed of forged nails) for knocking out the chaff and stem bits. If you're going to process it for spinning, it's good to have multiple hackles so that you can go from coarse to fine.
The tow that gets left on the hackle is really nice for fire starting -- especially when there are small bits of stem in it. That's actually where I use the majority of my tow.