I recently ordered a DSA 18". Have always wanted an FAL but put it off. Shot them many times over the years but never really messed with one and obviously never owned one. So, is there any sort of primer or things I should know about FALs before it arrives? I really regret not buying a parts kit and receiver years ago and having one built the many times I intended to do that. The prices of these things are nuts. 

For some of my specific questions...

1. Magazines. Stay with surplus? Aftermarket? 20s? 30s?
2. Gas system. Does it need to be dicked with at all or leave it alone?
3. Cleaning and lubing. Who, what, when, where and how?
4. Parts sourcing. Where? 
5. Reliability. Is there anything that I need to know ahead of time to help with reliability? 

Well, for lubrication, you lubricate the grooves in the receiver that the bolt carrier rides in; the horizontal surfaces that the bolt carrier's sides ride over; the entire exterior of the bolt body except for the bolt face; the interior surfaces of the bolt carrier; the locking shoulder; and the shaft of the bolt hold-open device. These parts are lightly oiled. I also do this with the surfaces that the charging handle slide rides in or on. Some people also grease the axis pins for the FCG and the return springs, as well as the frame lock assembly (internally), but I think most of that is for preservation. You can also lightly oil a cloth and run it through the gas tube.

IIRC, in dry and dusty/sandy conditions, it's supposed to be kept bone dry, except that a special graphite impregnated grease can be used on the sand cuts, if you have a bolt and carrier with them.

I only use grease on my FAL's these days. They don't know the difference, and they run just fine.

I've owned a number of FN FAL's and one DSA FAL. The main differences I noticed between the two are the FN FAL has a thick, black finish, where my DSA (Paratrooper model) had a parkerized finish. The FN finish looked nicer to me. And, the safety on the FN FAL was very stiff. The safety lever on the DSA FAL was a lot smoother and easier to engage/disengage. Also, the folding stock on the DSA FAL was a lot easier to fold than the stiffer FN FAL folding stock.
With my DSA FAL I had issues with DSA made magazines. The DSA magazines had issues with stripping rounds from the magazine. It would consistently fail to strip off the second round in the magazine. I never had this issue when using surplus OEM FN FAL magazines. I can't speak to accuracy differences between the DSA and the FN because I didn't own the DSA long enough to compare them.

For mags I really like Steyr mags with the witness holes. Surplus is best but not perfect. Some of the surplus mags are dented or bad feed lips. I also had some mags that I believe they were Israeli surplus that were tight as hell when locking in one of my receivers. Mooses mags are said to be perfect. DSA had problems with their early mags but I believe that they worked them out.

Don't mes with the gas system. It is generally a set it and forget it system. If it functions from the factory I wouldn't be moving anything unless you have a issue with excessive recoil or under powered ejection.

Go over to the FALFiles and join up.  DO NOT ORDER MOSES MAGS....dude has flaked out and has not been shipping orders, many people pissed off....

Got it in and other than slinging the empties into low earth orbit it worked great. 

I've been reading the threads on that stuff. I'll stick with ordering a few surplus every now and again. 

Finally got the confirmation on my stuff for FAL Files. Took a while. Now on to reading...

Adjusting the gas is simple and essential. Load one round into the mag. Insert the mag and load the round. Fire. If the bolt locks to the rear, turn the gas regulator counter clockwise 2 clicks. Repeat this until the bolt jams the fired case into the chamber. Turn the gas regulator 3 clicks clockwise, clear the fired case, load another round, fire. Bolt locks to the rear, you are done.