1. The RAN (in DH "shamta") says that a NIDUY is a kind of NEDER. In the former page we discussed that according to chamamin and rabi akiva and we didn't decide clearly. How the RAN decide?
2. (b) (R. Gidal citing Rav) One can take a vow to learn a specific tractate.
DID WE reject it> does he obligate to learn the specific daf?
1) I'm not sure which Ran you mean. Perhaps you mean the Ran on 8b, who writes that a Chacham can be Matir a Shamta although a Niduy is in the category of Nedarim regarding Hatarah.
Nevertheless, the Lashon of Niduy is not a Lashon of Neder. (Please cite your sources clearly, thanks D.Z.)
2) The Neder takes effect. Rambam, however does not record this Halachah.