The גמרא says (according to the מפרש) that ר׳ שמעון learns from the פּסוק of יין ושכר יזיר that a נזיר can’t drink wine of a מצוה which refers to קידוש והבדלה. The גמרא asks that you don’t need a פּסוק to tell you that because he is already מושבע ועומד מהר סיני. The מפרש understands that the wine of קידוש והבדלה is a חיוב דאורייתא, so your נזירות shouldn’t be חל on that since you are already מושבע ועומד. The תוספות רי"ד in פּסחים דף ק"ו quotes רש"י in the ספר הפּרדס as also holding like the מפרש that the wine of קידוש is דאורייתא. תוספות disagrees and holds that קידוש on wine is only דרבנן and asks several questions on the מפרש. The שיטה מקובצת in ד"ה אילימאasks some fascinating additional questions: first, who says you have to drink the wine? You just need to make קידוש on wine, but מדאורייתא you don’t need to drink it. Besides, someone else can drink it for you. Also, the שיעור for a נזיר is a רביעית, yet the שיעור forקידוש is a מלא לוגמיו, so he can just drink a מלא לוגמיו and then stop. The קרן אורה answers that according to רב יוחנן that last question would not be a question since חצי שיעור אסור מן התורה. There is a famous תוספות in שבועות דף כ"ג ע"ב ד"ה דמוקי that says that something that is only an issue of חצי שיעורisn’t considered something that you are מושבע ועומד on such that your שבועה should not be חל on it since חצי שיעור is just an איסור בעלמא. However, in this case we are talking about being מבטל a full fledged מצוה and you are certainly מושבע ועומד to do that. Finally, this is all in שיטת רבי שמעון who holds there is no שיעור for anything anyway and all the שיעורים we find are just regarding a חיוב קרבן so any amount would be a violation of his נזירות! Nonetheless, the קרן אורה agrees the other questions are strong and learns like תוספות that the גמרא is just asking rhetorically “are you מושבע ועומד? Certainly not since it’s not דאורייתא to drink wine by קידוש so no פּסוק should be necessary”. However, the קרן אורה points out that there are other דוארייתא מצוות relevant to drinking wine. In fact, there is a ספרי that quotes our פּסוק to teach you that a נזיר can’t drink מעשר שני wine. Nonetheless, our גמרא that doesn’t quote that must not consider it a real מצוה.

The משנה says that there is a קולא by נזיר עולם over נזיר שמשון in that נזיר שמשון can never cut his hair even if it is הכביד שערו and a נזיר עולם can. תוספות in ד"ה נזיר says that the נזיר עולם can cut some but not all of his hair. The חידושי הגרי"ז here points out that the רמב"ם in הלכות נזירות פּרק ה׳ הל׳ י"א holds that a regular נזירcan cut his hair (or at least won’t get מלקות) as long as he leaves a little bit of hair that you could turn the hair back over to the head (לכוף ראשו לעיקרו ). So if a regular נזיר can cut that far down, what היתר does a נזיר עולם have if its only a “partial cutting” but not a full cutting? תוספות even mentions that אבשלום got caught by his hair so that’s a lot longer than לכוף ראשו לעיקר. He says that theרמב"ם holds that a נזיר עולם can shave all the way down even closer than לכוף ראשו לעיקרו whereas a regular נזיר cant go past לכוף ראשו לעיקרו. It happens to be that תוספות on דף ל"ט holds that there is an עשה for cutting any amount so there is no question on תוספות since a נזיר עולם can cut some of his hair and a regular נזיר cannot. However, the רא"ש there even the עשה has a שיעור which needs a הסבר, ע"ש.