Question

Hello Rabbi,
How are you?
I wanted to ask a few questions, please.
1. Is there a dispute regarding the issue of which is stronger: the prior presumption of status or the current presumption of status? I understood that there are contradictory Tosafot on the subject. Or has some halakhic ruling or commonly accepted view been established on this matter?
2. Is there such a thing as rabbinic presumptions of status? I’m asking because I’m unclear about the beginning of tractate Niddah: is Hillel’s concern to render things impure retroactively rabbinic or from the Torah? Because on the face of it, it seems rabbinic, but the whole discussion there revolves around presumptions of status, and I understand that the whole concept of presumptions of status applies only at the Torah level.
3. I have another question about Tosafot HaRosh on page 2b: according to Hillel, it comes out that there is a flaw in the case of a woman who has blood, which undermines the presumption that she is pure and creates a doubt in her case. Add to that the fact that the pure items she handled were pure, and establish them in their prior presumed status—if so, why are they left in suspension? Rather, Tosafot HaRosh writes, in the section beginning “So too here: the blood is before you,” that apparently because she touched them, that undermined their presumption, and therefore they are left in suspension. But this is difficult for me from the case of a mikveh, because it had a presumption that it was full, and now that it is deficient, that undermines its presumption and creates a doubt. So here too, at the very least, it should undermine the presumption of impurity of the impure vessels and make them doubtful—yet the Sages say that everything is definitely impure. I’d be happy if you could explain whether this is in fact a valid question, and if so, how it is resolved.