RIE CEE

Yes, as it sounds Bachelor of Science. It means that it is a Bachelor's degree course and you can take IAS exam after this.

Please refer to the link provided below where details regarding payment for application fee is mentioned (Both Offline and Online method).
Regards.
https://www.shiksha.com/teaching-education/exams/rie-cee/application-form

Yes, nowadays, certification courses of everything are available so you may learn an Indian language at certification level. This will help in many ways. Secondly, you need to consult with the particular college from which you want to do.

Some popular reference material for RIE CEE exam is mentioned below:
Delhi University B.Ed. Bachelor of Education-Joint Entrance Exam
by Arihant Experts
IGNOU B.Ed. (10 Practice Sets)
by GKP
Learning And Teaching
by Suresh Bhavnagar and Premlata Maisnam
GGSIPU: B.Ed. Common Entrance Test Guide: B.Ed. Entrance Exam Guide (Popular Master Guide)
by RPH Editorial Board
Guide to D. U. B. El. Ed. Common Entrance Exam
by Nidhi Taneja and Student Aid Publications
BHU Banaras Hindu University B.Ed Bachelor of Education Entrance Exam
by Arihant Experts.

Please refer to the link to download the question papers: https://rielibrarymysore.wordpress.com/previous-question-papers/.

To get the details about syllabus for RIE CEE please visit the following link-
https://www.shiksha.com/teaching-education/exams/rie-cee/syllabus

Forms will be out in month of April tentatively. For further information and updates please visit the link-
https://www.shiksha.com/teaching-education/exams/rie-cee/dates

You can refer to Arihant experts, GKP, Suresh Bhavnagar, Nidhi Taneja as these are the best material available today, refer to any one of them and go through it completely.