Let me begin by thanking you for taking the time for this interaction – when we interact and listen to each other there is a chance that we can come closer to the truth.
Let me explain my position in light of your questions.
I believe that the 70 weeks of Daniel are contiguous – it seems that we are in agreement on this. I believe that the secular or conventional understand of history is incorrect and unbiblical. According to Daniel 11:2 there are only four Persian kings between Darius the Mede and Alexander’s victory over Darius II. Conventional history has about 10 kings between these two events. According to Zechariah 1:12 it was only 70 years since the destruction of the Temple in the second year of Darius II – again conventional chronology would have many more years between these two points in time. This article http://www.starways.net/lisa/essays/heifetzfix.html and this book http://www.amazon.com/The-Challenge-Jewish-History-Missing/dp/1937887316 will help you understand the Jewish point of view.
The Hebrew grammar of Daniel 9:25 does not allow the 7 weeks and 62 weeks to be joined. This is not a matter of punctuation – the Hebrew of the sentence does not allow the latter phrase (“return and be built…”) to stand by itself. The grammar dictates that the 7 weeks end with Mashiach Nagid who would be Cyrus and the 62 weeks end with the cutting off of Moshiach who would be the Sadducee high-priesthood that was terminated with the destruction of the Second Temple. The idea that one Messiah coming after 69 weeks is not viable on the basis of the Hebrew grammar of the verse.
Furthermore, both Cyrus and the high priest were called Moshiach in Scripture before this phrase in Daniel (Isaiah 45:1; Leviticus 4:3). The Davidic King that is to reign at the end of time is not. Therefore it would be logical to assume that Daniel is referring to people who we have already identified with this term and it is illogical to assume that he is talking of someone who has never been called by this title.
The “ending of sin” is the process of exile – as per Ezekiel 22:15 (the same verb is used there as in Daniel 9:24). This has two ramifications as it relates to this passage in Daniel – one is that the process of ending sin (of verse 24) is a process of exile that begins with the destruction of the Second Temple. And another ramification is that the word (Hebrew “davar” not decree which would be the Hebrew “gezerah”) to restore Jerusalem of verse 25 is the beginning of the exile process which is the destruction of the First Temple.
The concept of “ending sacrifices” spoken of in Daniel 9:27 is not a positive prediction and it has nothing to do with abolishing the efficacy of sacrifices – if that is what Daniel said he would be contradicting Moses who said that sacrifices do atone. He would also be contradicting all the prophets who predicted a return of the animal sacrifices with the advent of the Messianic era. Your understanding of this passage is also refuted by the fact that Jesus’ disciples were still bringing animal offerings for the expiation of sin in the Jerusalem Temple (Acts 21:26) see also https://yourphariseefriend.wordpress.com/2013/12/11/response-to-answering-judaism-acts-21-part-2/
You missed the point of the article (Letter to SY about Messiah). The point of the article is that Scripture gives us quite a bit of information on the subject of Messiah. You need to see the whole book in context. You cannot read Daniel apart from the rest of the Bible.
Let me finish by pointing out something about your writing style. I copied your comment onto a word document and it took up 23 pages. My humble request to you is – try to be brief. You do not add clarity by adding words. I don’t expect your writing style to change overnight – but please make it easier for people to follow this exchange.