Barbara y Alexis

my initial steps were the same as you.
the 800 number called for the appointment -- correct, that is not the NVC you talked to, it was direct to Havana, so I'd feel secure about that. you could always pay another $11 and call back to confirm.
then...i was told that Havana does not send notice that the packet is ready to be picked up, other people have said it depends on the location. my bf lives in Alamar and received (I think) a telegram telling him to go pick up his packet. maybe it was a letter he received, but he did receive some notice that he could go pick it up, and his name then was on a list admitting him to the embassy. there is a long line of cubans trying to get in, so if his name is on the list it's a lot faster.
it had DS 230 part 1 and 2; 156, 156K and 157 (they no longer call it part 3 and part 4)
you also should provide the affidavit of support (i forget the number for that form, but you can google it) the form and supporting documents, like your income, pay stubs, perhaps tax forms last 3 years, bank accounts. whatever would be convincing that you can support him / her as he arrives and gets up to speed.
it also has the list of hospitals where he can get the medical exam
seems like there was one other page of information (not a form)
oh yes, the "cover page" to all of this was a letter, and that said he should bring this letter to the appointment/interview. kind of like a reservation for the appointment, although it doesn't state the time and date of the interview, because that is what you made over the phone.
then of course you should bring some "proof of relationship" like emails, photos, letters, etc.
and perhaps an updated (new date) letter of intent (that you continue to support this petition and still intend to marry within 90 days)
hope that helps.