On question 4160 and others you mentioned the importance of learning now the Halachot of Pesach. I heard that this is a Mitzva M’deuraita (Biblical Mitzva), can that be true? Does then one have to have special intention for complying with it, as with other Biblical mitzvot?

Indeed Horav Shmuel Kamenetzky Shlit’a in Kovetz Halochos (Pesach 1: 1) mentions opinions that it is indeed a Biblical mitzva. Pri Megadim (E.A. 429: 1) quotes Maharsho (Suka 9a), that it is derived from the saying, that Moshe Rabbenu at the first Pesach instructed the nation to keep the second Pesach. However, from Beis Yosef (429), Lebush, Shulchan Aruch Horav (ibid) and others it is obvious that it is only a Rabbinical enactment.