Sheremetyevo Airport (SVO) Moscow
Trying to figure out the system at the Moscow aitport (SVO): you walk in, and besides some typical modern Russian kiosks, you see a ticket purchase counter -- not useable for getting your boarding pass. All the activity is on the right wall, at customs/departure. So already, the system's different than at US airports.
Instead of checking in and getting your boarding pass first, choose whether to go into departure customs: green line (nothing to declare) or red line (something to declare).
I said my goodbyes, then went through the green line. First thing was security. Woman asks "Seattle?" "Yes, Seattle", I say in English, to make it clear that I'm a foreigner and am, consequently, too silly to be dangerous. They x-ray the bags. And when I went to my baggage, the fellow said, in passable English, "please take your large bag to be inspected". I don't think I was being singled out. It seemed, I must say, much more like a security search than a "customs export" search. Not much vigilence about taking historical items out of the country, or lots of cash, or whether you were leaving with more than you came with. Inspector was very nice and completely minimal. Helped me shut my bag again, sent me to get my boarding pass.
Presented ticket & passport at the immediately subsequent ticket counter. Checked the large bag. No tag for the carry-on. Got the boarding pass, and went to the "passport departure" line. Wordlessly, the passport lady took my passport & ticket, communicated with the computer for a minute or two, stamped my visa. I went in ...
... to the Moscow airport gated section, for ticketed passengers only. Quite a scene: a dozen duty-free shops of fair size, not very busy, a bunch of bars, even an Irish pub and an Indian Restaurant. Smoking common, but not overwhelming. There's an upstairs area where people camp out, because you're not allowed into the gate until just before your flight (there's another security check there). This upstairs areas is a 15-foot-wide balcony, that wraps around the gated area, and looks over all the gates. It obviously had a different purpose, at another time. Right where the balcony turns, there's some power outlets, so if you have a russian plug, you can hypothetically sit and work ... without benefit of a chair, and on a floor that's mucky in places. Sitting against a wall, cross-legged, typing, balancing a notebook, is very hard on my 45-year-old back ... I really need to start doing yoga.
There's fee-based Wifi at the Moscow airport, by Tascom. You apparently pay for it in one of the shops downstairs (maybe -- there's a list of vendors at their website) but I enjoyed being offline.
Your flight boarding time is on your boarding pass, in a big font, and that's when the security check starts. Very thorough. Women do this work, searching you, waving wands, make you take your shoes off, X-Raying, metal detector walk-through, and going through every single thing in your carry-on luggage. This seems completely security-oriented, not customs-oriented.
Flight was uncomfortable for me because I had an aisle seat, and couldn't fall asleep in it. I couldn't get a vegetarian meal ordered -- Aeroflot is impossible to reach by telephone: get your ticket right, and get your meal right (all their US - Russia flights are non-smoking), when you buy the ticket, because you won't get another chance -- but luckily there was an extra in 1st class, and the crew gave me that -- potato & mushroom raviolis with asparagus. Not bad.
On the plane, you get a customs declaration. If you're a US citizen or green card holder, you can take up to $800 worth of purchases into the US. I guess you don't need receipts for this, if the value's pretty obviously low. Customs doesn't care about personal items at all -- your electronics, your shirts purchased in Russia, etc.
USDA-wise, as far as agricultural products go, I did have some rasberry jam with me, little hedgehog that I am, but I said I had no food. Jam is a condiment. I don't know if they would have taken it, if I brought it up, so I didn't. My wife & family spent hours in the forest picking those wild rasberries, so I wasn't keen to mention it. I know that the commercial grade stuff would probably pass, and that homemade stuff might not. Which is hugely unfair, so I was quiet on the subject.
At SeaTac, US Customs is pretty lenient towards native english speakers, I'd say. I interacted with five of these border cops. The first one, at the passport counter, asked me about some questions to determine that I was legit -- the passport could be fake, after all. He was making conversation "who do you know in russia?" "what do you do for a living?" etc.
You get your bags, in an interminable wait inside customs. When you get them, you head towards the exit, slowly, looking for one of the wandering customs agents. The one I got asked me what I had -- gifts etc? I said "small stuff, worth less than $100 ... I bought some shirts" and at that he handed me back my passport & form & waved me on. The next guy said less (he saw the previous conversation), another guy nodded me on, and the final guy took the form, on the way out. No inspection, but I think that's because I don't fit their profile.