1) Every once in awhile there is a dump of new seforim onto hebrewbooks.org and when I see that I start browsing here and there. In a sefer they just put up called Noam Amarim, the Sassover Rebbe notes that it says by mattan Torah that the people stood וַיִּֽתְיַצְּב֖וּ בְּתַחְתִּ֥ית הָהָֽר, at the bottom of the mountain. A person should want to climb and grow in ruchniyus, but sometimes a person falls or finds himself stuck at rock bottom. Our parsha teaches that Torah is addressed even to that person, to those stuck on the bottom of the mountain.
The Rebbe also says he was asked an interesting question that he had never thought of before. If you look in P' Masei, you will see that Sinai is the 13th stop that Bn"Y came to after leaving Egypt. Why was it on the 13th stop in particular that Torah was given? I usually don't like these sorts of questions. If it had been the 12th or 11th of any other number stop, you could ask the same thing. The Rebbe did like it, and connects it to the 13 midos.
2) On to a more halachic topic. Did Klal Yisrael says a birchas haTorah before kabbalas haTorah or not? And if they did, what did they say?
Before answering that question, first point that needs clarification is why a birchas haTorah might be required. It says in SA 47:4 המהרהר בדברי תורה א"צ לברך. True, GR"A disagrees, but the question here is not only according to shitas haGR"A. The gemara (Br 20b) writes that בעל קרי מהרהר בלבו to fulfill the mitzvah of shema. The gemara comments: מר רבינא זאת אומרת הרהור כדבור דמי because if hirhur was not equivalent to dibur, how could the baal keri be yotzei? The gemara says perhaps this is no proof. If הרהור כדבור דמי, why bother with hirhur -- why not just say the words? The gemara answers כדאשכחן בסיני. Explains Rashi: שהפרישן מאשה דכתיב אל תגשו אל אשה (שמות יט) ועל פרישה זו סמך עזרא לתקן טבילה לבעלי קריין קודם שיעסקו בתורה. Saying the words requires a higher level of tahara, as we see from mattan Torah, that hirhur does not.
What words were said by Bn"Y at Sinai? Tos on the spot answers that when Bn"Y heard mattan Torah, shome'a k'oneh, it was as if they said the words. We see an interesting chiddush from Tos that the din of shome'a k'oneh is not just a means to be yotzei a bracha, but it counts as if you actually articulated the words.
Did that kiyum of talmud Torah which Bn"Y fulfilled at mattan Torah via shome'a k'oneh require a birchas ha'Torah? This question was posed to R' Shteinman, and what bothered R' Shteinman's interlocutor is the text of the bracha. How can you say אשׁר בּחר בּנו...ונתן לנו את תורתו when the event hasn't happened yet?
The very same question might be asked regarding the Avos. Assuming the Avos kept all the mitzvos, which would include birchas haTorah especially according to the shitos that hold it is d'orasya, how did the words make any sense? Did they have a different nusach ha'bracha?
I would add one detail to strengthen the makshan's question here. As we've discussed before, the Tur writes that when one recites the bracha of אשׁר בּחר בּנו...ונתן לנו את תורתו one should have kavanah for the mitzvah of remembering maamad Har Sinai, which Ramban counts as a separate miztvah. Bach explains that the Tur was bothered by the fact that we have multiple brachos for birchas haTorah. Why isn't one bracha enough? It must be that one of the brachos is not on the act of learning, but rather on remembering maamad Har Sinai. How does it make sense to say such a bracha before maamad Har Sinai had occurred?
R' Shteinman held that perhaps they only recited the first bracha of לעסוק בּדברי תורה since there was no other option.
I think there is another approach one can take. The source for the din of birchas haTorah is a pasuk in Haazinu: אמר רב יהודה, מניין לברכת התורה לפניה מן התורה, שנאמר כי שם ה׳ אקרא הבו גודל לאלקינו. This appears after the final mitzvah of writing a sefer Torah. Netziv comments in Devarim 31:32 that it's no wonder that this mitzvah of birchas haTorah appears only after the 40th year in the midbar at the end of Devarim. Until the entire Torah was put into writing, no birchas haTorah could be recited:
עיקר הלימוד כתוב להלן (פסוק ל׳) ״וידבר משה באזני כל קהל ישראל את דברי השירה הזאת עד תומם״, וזה היה אחר שנגמרה כתיבת הספר תורה עד תומם (פסוק כ״ד), ואז היה אפשר להקהיל את העם ולומר השירה בברכה, כמו שאמר (להלן לב,ג) ״כי שם ה׳ אקרא״, אבל בספר תורה חסר אי אפשר לברך, וא״כ לא היה יכול משה מיד להקהיל קודם שהודיעו הקב״ה כל פרשת ״וזאת הברכה״ וגמר כתיבת ס״ת עד ״לעיני כל ישראל״
This fits perfectly with R' Chaim Brisker's chiddush that birchas haTorah is on the cheftza shel Torah -- the text -- rather than the chovas ha'gavra of the mitzvah of talmud Torah. This is why even according to the SA, who paskens that women cannot recite brachos on mitzvos they were not commanded to do like sukkah or shofar, holds that they may recite birchas haTorah. Even if women lack a chovas ha'gavra to learn, it is the text itself which requires having a bracha recited over it. Pre-completion of the Torah there was simply no cheftza upon which to recite a birchas haTorah.
Therefore, at mattan Torah, given that there was no text of Torah in a completed form that yet existed, a birchas haTorah may not have been applicable.