For education documents, go to Amist Kilo's Ministry of Education's Examinations office (in front of Patriarch's residence) with your original documents. You pay 35 Br and they'll authenticate it (stamp and signature on the back). Then you take it to MoFA in Kazanchis, and pay 100 Br. They'll authenticate it on the back as well.
Only the principal applicant's documents must be authenticated.
For translation, you can use any official translation company. I used one approved by the French Embassy since the documents are in French. There are many of them in Stadium. I used Yeshimebet since that's the one the Embassy recommended. The translation is terrible, by the way, but I did as they asked.
I don't know how to authenticate marriage certificates, so someone else will have to answer that part.
Congrats 1danny!!!