I can field the Etruscan question (I've been trying my own efforts at reconstructing it lately). Aye indeed, as Annis put well, the Greeks did not borrow from the Etruscans (and looked down upon them for their relative depravity). The Etruscans, in fact, learned the alphabet from the Greek colonists in southern Italy, and would always recite and learn every letter of their borrowed version, even especial Greek letters they never used themselves. One addition they made to the alphabet, however -- and possibly to all European languages themselves which would develop after -- was the letter representing "F," which was drawn in the Etruscan alphabet like an Arabic numeral 8
. They of course had the phi
from the Greeks, but this letter wasn't produced in Greece like the 'F'-sound in philosophia
until long after classical times. Phi
, instead, was a bilabial fricative, a whistling sound caused by the vibration of air between the lips when pursed. (For those unfamiliar, try making the shape of 'oo' with the lips, and then blow air as if to whistle weakly.) Though Etruscan had this sound and letter from the Greeks, the "F," on the contrary, was alien to Indo-European languages.
The Norse and other Germanic runes are derived from the Etruscan alphabet (many similarities are quickly noted with a direct comparison). The incredibly civilized and sophisticated Etruscans often traded with the rustic barbarians to the north, and no doubt highly influenced their culture. Even the Etruscan word of "god" and "gods," as, æsr
, are exactly the same in Old Norse. Thus the Etruscan "F" may have been what brought the Germans to use the sound in their languages, just as the Latins adopted it as well. The proper phi
sound was not in Latin, however, and perhaps the Romans' use of "F" in so many words caused the Greeks, once conquered by Rome, to make the labio-dental fricative instead out of its ease of pronunciation. Or maby the Greeks just got lazy.