1) Ramban in two places writes that there is a mitzvah to remember ma’amad Har Sinai, yet in each place he defines what that mitzvah is a little differently: in Sefer haMitzvos (lavim that the Rambam forgot #2) he counts forgetting ma'amad Har Sinai as a lav, “rak hishamer lecha.. pen tishkach es ha’devarim asher ra’u einecha,” yet in his commentary on the Torah (Devarim ch 4) he focusses on the end of that pasuk, “...v’hodatam li’vanecha,” and counts it as a mitzvas aseh to transmit the memory of ma'amad Har Sinai to the next generation.
Ramban is difficult to understand as it seems to be against a Mishna. In Pirkei Avos (3:8) the Mishna writes that someone who deliberately forgets their learning violates the issur of “pen tishkach.” According to Ramban, this pasuk is an issur of forgetting maamad har Sinai, not an issur of forgetting Torah.
(I see on my son's blog he raised this same question last August. Only because he's my son I'll nitpick on one point of his. It's not really true that "everyone asks on the Ramban" (as he wrote) from this Mishna. Actually, the surprising thing is that the Megillas Esther on Sefer haMitzvos does NOT raise this question at all. Instead, he asks on the Ramban from a gemara in kiddushin (30) that darshens from “v’hodatam li’vanecha v’livnei banecha” that there is a mitzvah to teach torah to one’s grandchildren, implying again that this pasuk has to do with limud haTorah, not remembering ma'amad Har Sinai. Ramban himself notes that difficulty and tries to resolve it, albeit in a way that the Mg"E finds unsatisfactory. In any case, why are they bothered by this gemara when you have a clear Mishna in Pirkei Avos to ask from?)
Rav Eliyahu Bakshi Doron, the former Rishon l'Tzion, in his Shu"T Binyan Av vol 3 addresses this Ramban in two places (#20 and #47) and suggests (my son quotes a similar answer from R’ Povarski) that when you learn torah with an awareness that this is the dvar Hashem received at Sinai, it becomes a different limud –- it becomes something unforgettable. If the learning is just stam a subject, then it makes less of an impression.
This is how Ramban understood the Mishna in Avos. If you forget your learning, then that’s a siman that you are missing that awareness of maamad Har Sinai which is a mitzvah to always have in mind.
I think that may be pshat in the gemara (Brachos 22 for those of you learning the daf) that learns that a ba'al keri cannot learn Torah without going to mikvah based on a hekesh of "v'hodatam levanecha", i.e. talmud Torah, with "yom asher amadita b'Chorev", i.e. ma'amad Har Sinai -- just like the latter was b'yirah and tahara, so too must the fomer be done b'yirah and tahara. According to Ramban, "v'hodatam livanecha" has nothing to do with limud haTorah -- the whole pasuk is talking about ma'mamad Har Sinai. What does the gemara mean?
Based on Rav Bakshi Doron's yesod, it makes perfect sense. The gemara is telling us that you have to pass on not just what was learned at Sinai, but the whole context of the experience, the yirah, the awe, etc. If you are learning in a state of tumah, than it shows you failed to appreciate what ma'amad Har Sinai was all about.
2) The gemara (Brachos 6 - more fodder for those learning the daf) writes that a person who is mesamayach a chasan and kallah through kol sason v’kol simcha will be zocheh to Torah, which was given at sinai through 5 kolos -– 5 times in our parsha the Torah mentions “kol” in connection with mattan torah.
The Iyun Yaakov on the Ein Yaakov explains the midah k’neged midah: a person who invests in bringing simcha to others is himself zocheh to simcha. What bigger simcha can Hashem give a person other than Torah -– “pikudei Hashem yesharim mi’samchei lev.” (I haven’t done a search, but it would be nice to find a makor that says it works in the other direction as well, i.e. a source that says someone who is sameich in their learning and needs a shiduch will be zocheh to one. It would make for a good segulah.)
Asks the gemara: if you look through the parsha and count you will actually find 6 mentions of kol, not 5. Right after the aseres hadibors the Torah writes that the people were “ro’im es ha’kolos,” they had synesthesia and were able to see the thunder sounds with their eyes.
Answers the gemara: that pasuk is describing the kolos were experienced before mattan Torah, but is not an additional "kol."
Imrei Emes asks the obvious question: if the pasuk is describing the nature of the "kolos" that took place before or during mattan Torah, why does the pasuk appear only after the aseres ha'dibbros? Why not put it beforehand, when those other kolos are mentioned?
The answer gets to the heart of what mattan Torah was all about. It wasn't just a transfer of information from shamayim to us. It wasn't just a “revelation” of laws. Mattan torah was a transformation of who we are as a people and who we are as individuals. Chronologically speaking, “ro’im es ha’kolos” happened before mattan Torah. However, the people could not digest the experience and appreciate it in the state they were in. It was only after they received the Torah and their neshomos were transformed that they were able retrospectively to understand those kolos that they had experienced beforehand.