(1)Tosphos 94B d'h v'ain implies that even according to R' ELiezer according to Abaia, if we hold ain shochtim v'zorkim al tamei sheretz one who is not tovel is chayev kares (per Maharsh"a) yet one is potur from pesach rishon if he is just outside the azarah even though he could have stepped back inside. How do we know this distinction? Apparently this is what the gmorah is resolving when it says derech r'chokah l'tohor v'ain derech r'chokah l'tameh but the explanation given by Rash"i both here and on the previous daf only seems to be applicable to the shitah of shochtim v'zorkim al tameh sheretz.
(2) The gmorah on the top of 93A assumes from a davar pashut that even for a tameh sheretz (according to the shitah ain shochtim...) if one were to include him, lo hurtzah, yet there is a machlokes amoraim by one who is b'derech r'chokah. Why is it poshut by a tamei and not by mi sheb'derech r'chokah?
Thank you V'Kot Tuv,
(1) The MAHARSHA writes clearly on 69b, regarding the Beraisa there that says that according to the opinion that holds "Ein Shochtin v'Zorkin Al Tamei Sheretz" (that is, until he immerses in a Mikvah), the person who is Tamei is required to be Tovel, and if he does not, he is Chayav Kares. The reason is because everyone agrees that "Shochtin v'Zorkin Al Tamei Sheretz" after he was Tovel . The only argument is when he has not yet been Tovel, and the argument is whether or not we assume that he will be Tovel and eat in the evening, as TOSFOS (93b, DH Derech) and most of the Rishonim explain. Therefore, even the opinion that holds "Ein Shochtin v'Zorkin" agrees that the person is required to be Tovel in order for it to be possible to do the Shechitah and Zerikah for him.
(2) According to the opinion that holds "Ein Shochtin v'Zorkin" it is Pashut that it is "Lo Hurtzah," since he derives this from a Pasuk ("v'Chi Yamus," on 90b). According to that opinion, the Gemara indeed concludes that we learn from one who is Tamei that it is also "Lo Hurtzah" for one who is b'Derech Rechokah -- through a Hekesh (or a Meh Matzinu -- see Tosfos 93a, DH Hachi Garsinan) -- just like it is "Lo Hurtzah" for someone who is Tamei Sheretz.
According to the opinion that holds "Shochtin v'Zorkin," it is Pashut that the "Tamei" mentioned in the verse is not referring to Tamei Sheretz, but to Tamei Mes on the first day of his Tum'ah, who is going to be Tamei in the evening as well. In such a case (Tamei Mes) it is Pashut that "Lo Hurtzah," since he is not fit to eat (Gavra d'Lo Chazi l'Achilah), and in order to be "Shochtin v'Zorkin" for someone, he must be a Gavra d'Chazi l'Achilah (78b; see Tosfos here, DH d'Iy).