Baba_Agba :
For the Evidence of Support, you can provide any combiantion of the 3, which means you can provide one ( any one )of the mentioned documents, two ( any two ), or the three of them.
Remeber that you better be safe than sorry. Bring as much as you can.
So, the I134 is good. Still, it would be better if you could show your own funds, instead of just relying on other people's money.
Don't get me wrong, the I134 should be enough. For my own peace of mind, I prefer to be safe and overprepared...
Vania :
The principal applicant has to show the documents I listed. Beneficiaries have to show most of them ( proof of termination of prior marraiges, birth ....). The only one that is not required for beneficiaries is the High School diploma : only the principal applicant has to prove it.
For translations, it depends on your consulate/embassy.
For CP in France ( my experience ), documents written in French or English were accepted.
Check for your location. Even if you have to pay a fee to contact the onsulate, it might save you a lot of money ( certified translations are very expensive )