Here is a quote from the Code of Federal Regulations: 

8 CFR 103.2 (b)(3)

(3) Translations. Any document containing foreign language submitted to the Service shall be accompanied by a full English language translation which the translator has certified as complete and accurate, and by the translator's certification that he or she is competent to translate from the foreign language into English.

-- Revised as of January 1, 2010

It depends on requirements of the receiving office. If you have a short deadline or limited budget, and notary is not specifically required, pdf-file with certified copy of translation can be your choice as the quickest and cheapest alternative.

No. USCIS requirements are as follows:

Please submit certified translations for all foreign language documents. The translator must certify that s/he is competent to translate and that the translation is accurate. The certification format should include the certifier's name, signature, address, and date of certification.

USCIS no longer routinely requires submission of original documents or "certified copies." Instead, ordinary legible photocopies of such documents (including naturalization certificates and alien registration cards) will be acceptable for initial filing and approval of petitions and applications.

At the discretion of the officer, original documents may still be required in individual cases.

-- U.S. Citizenship and Immigration Services. General Tips on Assembling Applications for Mailing. Last updated: 12/03/2010

You receive pdf-file with certified copy of translation, regardless of whether notarized copy of translation have been ordered or not. Translation is appeared on the company professional letterhead, and includes a copy of original and signed Affidavit of Translation Accuracy (certification of translation). Furthermore, the translation can be verified online by a receiving official. Instructions are provided. Notarized copy of the translation can be ordered lately, if necessary.