Resources for Yevamos daf 61
1. The גמרא says that according to רבי שמעון בר יוחאי an עכו"ם is not מטמא באוהל. תוספות in ד"ה ממגע says that we don’t pasken like רשב"י since the משנה in אוהלות goes like the רבנן who say they are מטמא באהל. However, theרמב"ם in הלכות טומאת מת פּרק א׳ הל׳ י"ב paskens that an עכו"ם is not מטמא באוהל but is מטמא במגע ומשא. That would seem to fit exactly with רשב"י in our גמרא. It also fits with the גמרא in ב"מ דף קי"ד that says that אליהו was walking around a בית הקברות of עכו"מ even though he was a כהן. The יראים as quoted by the הגהות מימונית there has a third very surprising שיטה. He says that a נכרי is not מטמא at all—not באוהל and not במגע ובמשא. This would seem to be against all the גמרות. רבינא says explicitly that everyone agrees there is טומאת מגע ומשא! Theמשנה למלך in הלכות אבל פּרק פּרק ג׳ הל׳ ג is bothered by this and has a fascinating explanation. He says that the יראים didn’t mean that there is no טומאת מגע ומשא. Rather, there is טומאה but it isn’t the kind of טומאה that a כהן needs to stay away from (similar to a נבלה which is מטמא and a כהן is still allowed to get that טומאה). By מלחמת מדין they still needed to be מטהר themselves since they did become טמא במגע, but it was a טומאה that a כהן is allowed to do. The משנה למלך even goes so far as to suggest we should pasken like the יראים since there is a halachic ספק ספיקא: there is a שיטת הראב"ד often quoted as saying that if a כהן became טמא once in his life there is no איסור for him to become טמא again since he is already טמא. That would make every כהן today not have a problem walking into any cemetery (others dispute that the ראב"ד meant this). Even if we don’t pasken like that, maybe we pasken like the יראים. Hence a ספק ספיקא. Nonetheless, the שולחן ערוך in סימן שע"ב says one should be מחמיר that קברי עכו"ם are מטמא באהל.
2. The גמרא brings רבי מתיא בן חרש who says that a woman who is a ספק סוטה and her husband is בא עליה is considered a זונה. רבי עקיבא איגר asks in his חידושים here why do we need to come on to the fact that she became a זונה with this ביאה? Even if it didn’t make her into a זונה, her כהן husband still can’t be married to her since if a ספק סוטה is נבעלת to her husband before she drinks the סוטה water then the סוטה water won’t work since he isn’t "מנוקה מעון". If the סוטה water doesn’t work, then she remains אסורה to him because she is a ספק זונה since she may have been with another man! So what do we gain by calling her a סוטה from being with the husband?!He answers that a נפקא מינה would be מלקות, since if the reason she is אסורה לכהונה is just because of the קינוי וסתירה then it would not have מלקות since it is just a ספק. However, once he is בא עליה before she drinks then he is has done a ואדי איסור which would make her into a ואדי זונה who gets מלקות. The קובץ הערות in סימן ט"ו אות ט"ז-כ"א points out that רע"א seems to be taking sides in an interesting חקירה that the קובץ הערות is not sure about. The קובץ הערות wonders what would happen if for example a נביא came and told us after the husband was בועל his wife before drinking the סוטה water that she really wasn’t מזנה תחתיו. Would we say that the husband didn’t do an עבירה by being בועל her without השקאה since it turns out she was never guilty and the איסור is only מספק, or do we say that since the Torah forbade it מספק it becomes a ואדי איסור even if we find out later she was innocent. רע"א must have assumed it was an איסור ואדי so she becomes a זונה with מלקות.
Rabbi Millman's Marei Mekomos Halacha
New Daf Hashavua newsletter - Shavua Matters
Rabbi Mordechai Papoff - English Topics
Rabbi Yaakov Blumenfeld - Shakla Vetarya
Rabbi Azriel Katz - Meforshim Overview
Rabbi Yishai Rasowsky - Tosfos Synopsis
Rabbi Yechiel Grunhaus - Points to Ponder