You will have to remember, that the concept of SATAN was taken from the persians.. and the 'salvation' was actually retrofitted onto the old testament when it comes to translations from the hebrew, even though there are other terms that are just as good or not better.
There is no concept of 'salvation' as the christian knows it in the Jewish faith. The Latin terms for salvation and savior came directly from cult of Ceasar Augustus.
As for Satan, the Jews took the concept from Persia. The concept that Satan was this demigod that was seperate from God came from Greek influnces. In the Jewish religion, Satan was just an angel of god, and (this is an important thing), angels did not have free will, therefore they could not revolt against god. The term 'satan' might have come from Judaism, but the nature of Satan came from the persians.
And let us look at the concept of "Hell". There is no concept of "hell" as a place of eternal torture, but the Roman Catholic Church adopted the concept from Zoroastrianism, mixed in the concept of Sheol (the grave) from Judaism, and made 'hell' a place of eternal torment.
Now, you might say that 'almah' means 'virgin' because it was translated to pathenos in the greek. I happen to disagree. If you look at rape of Dianah in Genesis 34, she was referenced as 'parthenos' even after she was raped by Shechem. There is also the use of 'almah'
in the song of solomon, which a young lady is refered in a very erotic and sexual manner (and most assurdly not a virgin).
So, to claim that the concept of a virgin birth for the messiah is in the old testament is just plain incorrect. There are many other sources for that concept, but not from the passage you are pointing too. Besides, if you read Isaiah 7:14 in context, it is fairly obvious that Isaiah was refering to his own wife (the prophetess), and not someone who was born 600 years later.