how will we know what to do? reviving lost mesorah; issurei achila -- issur gavra vs issur cheftza

1) One of the things I like about R' Shteinman's torah is that his questions/answers are not far-flung lomdus, but are, dare I say it, rooted in common sense.  On this week's parsha he quotes the Chofetz Chaim's charge to learn kodshim so that once geulah comes b'karov gedolei yisrael will be able to pasken on issues relating to the mikdash and kodshim.  R' Shteinman asks: how are these gedolim supposed to figure out what to do?  He quotes that the Ponivicher Rav dealt with this very question and responded that he will just follow the Chofetz Chaim's lead.  That just kicks the can down the road.  How is the Chofetz Chaim supposed to figure out how to pasken?  And if you say that we will have a techiyas ha'mesim and can just ask Moshe or Aharon, then why bother learning kodshim to try to figure everything out?  We can just ask Moshe and Aharon?  

I've had a similar thought since I began wearing techeiles.  When you order techeiles from the Ptil Tekhelet site they give you a whole menu of options to choose from as to which shita to follow in tying the tzitzis.  How do you know what to choose?  Any mesorah as to what to do has been lost for at least 1200 years or so!  We are halachically flying blind.  And that is assuming you even want to wear techeiles, which a large segment of the Jewish world, for one reason or other, has yet to be convinced to start doing.  Imagine we somehow finally fulfill the mitzvah of binyan beis ha'mikdash in our times.  Any mesorah as to what to do has been lost for even longer than the mesorah of techeiles.  Already in Mishnayos (Midot 2:5) we have Tanaim saying about lishkos of the azarah אָמַר רַבִּי אֱלִיעֶזֶר בֶּן יַעֲקֹב: שָׁכַחְתִּי מֶה הָיְתָה מְשַׁמֶּשֶׁת that they forgot what the space was used for.  How are we supposed to know?

2) While on the topic of R' Shteinman's torah, here is another interesting question he raises:

 וּכְלִי־חֶ֛רֶשׂ אֲשֶׁ֥ר תְּבֻשַּׁל⁠־בּ֖וֹ יִשָּׁבֵ֑ר וְאִם⁠־בִּכְלִ֤י נְחֹ֙שֶׁת֙ בֻּשָּׁ֔לָה וּמֹרַ֥ק וְשֻׁטַּ֖ף בַּמָּֽיִם (6:21) 

Is this a mitzvah or a matir?  Meaning, what if you want to just throw the utensils in the garbage?  Is there an obligation of מֹרַ֥ק וְשֻׁטַּ֖ף בַּמָּֽיִם or is it just a matir if you want to use the kli? 

Another interesting one: Off the cuff I would have assumed that when you have a lav ha'nitak l'aseh, the aseh has to be done by the person who violated the lav in order to give him a ptur from malkos.  You see from our parsha that is not true   The gemara writes that there are no malkos for the issur nosar because it is a lav ha'nitak l'aseh, but it sounds like the mitzvah of burning nosar (6:17) can be done by anyone.  

And if you like a Brisker style chakira, R' Shteinman occasionally throws those out there too: The gemara (Zev 87) raises the question of whether something hung in the airspace above the mizbeiach counts as being on the mizbeiach itself or not.  Yesh lachkor whether the gemara means the airspace is the makom mizbeiach, or whether it's not the makom mizbeich, but it has the din of makom mizbeiach.  

I could go on all day quoting interesting points from the Ayeles haShachar, but I don't have all day so תן לחכם ויחכּם עוד.  That was just to whet the appetite.  Maybe I should do something like that every week.

3) וְהַנּוֹתֶ֣רֶת מִמֶּ֔נָּה יֹאכְל֖וּ אַהֲרֹ֣ן וּבָנָ֑יו מַצּ֤וֹת תֵּֽאָכֵל֙ בְּמָק֣וֹם קָדֹ֔שׁ בַּחֲצַ֥ר אֹֽהֶל־מוֹעֵ֖ד יֹאכְלֽוּהָ

Based on the language of the pasuk the Malbim makes what sounds like a Brisker chiluk .  He writes that when the Torah uses the term אוכל, it is referring to the gavra, but תֵּֽאָכֵל֙, passive voice, nifal, refers to the cheftza, the item being eaten.  Nafka minah: whether or not you need to eat a shiur.  When the object is being referred to, the shiur is any amount; when it is the person eating being referred to, then אין אכילה פּותה מכּזית (see Beis haLevi quoted in this post.)

 יש הבדל בין פעל ׳אכל׳ בקל ובין הנפעל. שפעל ׳אכל׳ בקל מוסב על האדם האוכל ולא יקרא אוכל אלא בכזית; שפחות מזה נקרא ׳טועם׳ – ״כי טעמתי מעט דבש״ (שמואל א י״ד). וכמ״ש בספרא לקמן [(פרשה י מ״י) (אחרי מות פרק יב מ״ב) (אמור פרק ד מט״ז) (אמור פרק ו מ״ג) ובפסחים (דף לב.)] ״סתם אכילה בכזית״. אבל הנפעל מוסב על הדבר, ואף אם נאכל כל שהוא – הגם שלא יקרא ׳אכילה׳ מצד האוכל שלא אכל רק טעם – מכל מקום הדבר ׳נאכל׳ ואיננו. וזהו שאמר בספרא שלכן שינה ואמר ״מצות יֵאכל״ בנפעל ולא תפס הלשון שדבר בו עד עתה – ״יאכלו אהרן״ ״יאכלוהו״; והיה לו לומר ״מצות יֹאכלו״. ללמד שאף שלא נשאר רק מקצתה - בכל זאת תאכל.

With this he explains the Rambam (Cu"m 1:7) who writes that the shiur of the issur achilas chameitz is a kol she'hu:

האוכל מן החמץ עצמו בפסח כל שהוא הרי זה אסור מן התורה שנאמר לא יאכל

The Kesef Mishna asks two questions, the second of which is . ועוד קשה דאי מקרא איפכא ה"ל למילף מיניה דלא יאכל שיעור אכילה משמע וצ"ע. It uses the word achila, so how can the Rambam say you are chayav on less than a k'zayis?  Answers the Malbim: because it is nifal, passive voice, a din in the cheftza, not the gavra, so there is no shiur.

The problem is if this is correct, then the same chiddush should apply to other issurim as well written in lashon nifal:

וְכִֽי־יִגַּ֨ח שׁ֥וֹר אֶת־אִ֛ישׁ א֥וֹ אֶת־אִשָּׁ֖ה וָמֵ֑ת סָק֨וֹל יִסָּקֵ֜ל הַשּׁ֗וֹר וְלֹ֤א יֵאָכֵל֙ אֶת־בְּשָׂר֔וֹ וּבַ֥עַל הַשּׁ֖וֹר נָקִֽי׃ (Shmos 21:28)

 וְכָל-הַשֶּׁרֶץ, הַשֹּׁרֵץ עַל-הָאָרֶץ--שֶׁקֶץ הוּא, לֹא יֵאָכֵל (Vayikra 11:41)

Is there an issur for eating less than a k'zayis of shor ha'niskal, or of a sheretz?!

Ohr Sameiach explains that the Rambam's chiddush may be unique to chametz based on the context of the pasuk:

וַיֹּ֨אמֶר מֹשֶׁ֜ה אֶל־הָעָ֗ם זָכ֞וֹר אֶת־הַיּ֤וֹם הַזֶּה֙ אֲשֶׁ֨ר יְצָאתֶ֤ם מִמִּצְרַ֙יִם֙ מִבֵּ֣ית עֲבָדִ֔ים כִּ֚י בְּחֹ֣זֶק יָ֔ד הוֹצִ֧יאה׳ אֶתְכֶ֖ם מִזֶּ֑ה וְלֹ֥א יֵאָכֵ֖ל חָמֵֽץ׃ (Shmos 13:3)

The pasuk is talking about Pesach Mitzryaim, not Pesach as celebrated for future generations.  At the time of that Pesach, we had not undergone the geirus of mattan Torah and in effect, were still bnei Noach.  Rambam says in Hil Melachim that there is no concept of shiurim for a ben Noach (see this post); therefore, the issur chametz would be violated even on a kol she'hu.  Once the issur was established, it carried over the Pesach doros in the same way.