Agriculture

No, it's not mandatory. You can apply for M.Sc in forestry. As M.Sc. Is a good option. As Masters degree can give you good career opportunities. You can go through this.
Good luck.

I am attaching a link here in this. You will get most of your answer of your query. You can go this link. You will get clear your doubts:
http://www.jau.in/index.php/academics-top/polytechnics-top/polytechnic-in-animal-husbandry.
Good luck.

B.Tech Admissions in GB Pant University are done through JEE Main Rank and Counselling conducted by Uttarakhand Technical University. As stated on there website. You will get more details about Admission on there official website. They also had a Contact Number listed on there website. You can call on that and Love your queries. I have attached the link below. http://www.gbpuat.ac.in/index.html
You can also predicte your college using JEE Mains 2018 College Predictior. Link is below. https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor
Good Luck!

If you have your application form which you filled for the entrance exam, then you can go to any cafe with that form. They will help you. As I did that once. I don't have idea but they will do something and it is possible to get your roll no again. Good luck.

Yes, you can enter PAU for B.Tech without your JEE marks. You have to give their CET (Common Entrance Test). The last day for the same is 11th May and with late fees its 18 May.

In M.B.A. (agriculture) student learns the production and distribution process for foods and fibers, as well as related business principles. M.B.A. (agriculture) providing a comprehensive coverage incorporating the foundation, functional and elective courses relevant to management.
MBA in Agriculture is often referred to as specializing in either agricultural economics or agribusiness.
Students obtain pertinent skills that allow them to make sound financial and business decisions in the agriculture industry.

There are over 14 B.Sc in agriculture colleges in Uttar Pradesh offering 14 courses. Please refer to the link provided below for a detailed list of these colleges. You should be able to navigate to the top colleges on the list using the filters on the web page.
https://www.shiksha.com/science/colleges/b-sc-agriculture-colleges-uttar-pradesh