This sounds very familiar! We had to get visas for our kids -- they become US citizens upon arriving in the US, which meant we had to get (pay for etc) home-country passports (which at least are cool souvenirs) -- and go to the US Embassy (for Max, in Moscow) and Consulate (for Sam, in Guangzhou). Lots of paperwork! But just a tiny percentage of all the paperwork we had to do for their adoptions. SO glad we're done with all that.
But, yeah, there are lots of rules about embassies, what you need, what you can & can't bring in with you. Now you know, should you ever need to go back...
We had the same problem at the US embassy in London last week - they didn't look at most of the paperwork they asked for and I spent ages pulling together, and you weren't allowed laptops or bags in so Alex had to run to a local bag store to deposit his there and still get back in time for our appointment. Thankfully Ali was chilled out as there were a lot of people in the London embassy! They did give us visas at least :-)
Huh, it seems like they should advertise the laptop rule more! We could have bags, but we had to open it and show what was in it through the window while standing outside. Then they put it through the scanner once we were let in.