B.Sc

You have to fill the PUCET UG form online.
Forms are available at pucet.pichd.ac.in

Yes, you can apply. Forms are out at official site of PU today.

Hi Harini,
Yes, you can get direct admission for Integrated M.Sc (B.Sc+M.Sc 5 years) in Padmavathi College, only if you a native from Andhra Pradesh and Telangana. There are 30 seats for direct admission in Padmavathi College. But, it is a self-finance scheme, which means the course fees will be little bit more than the regular student (admitted via entrance). For more information please visit: http://www.spmvvdoa.in/documents/intructions_for_direct_admissions-2018-19-26-03-2018.PDF

In-order to get admission in Ranchi University for Post Graduate course in Botany, you have to clear the entrance exam organized by the university.
Admission Eligibility: B.Sc/ B.Sc (Hons.) with 55% aggregate marks.
For More Info please visit: http://www.ranchiuniversity.ac.in/2014-03-31-05-27-00/2014-04-02-06-49-40/botany.html

Yes. He can go ahead to complete is MBA in hotel management. This will add value to his resume and fetch him many opportunities to work in the hotel industry.

No, minimum percentage requirement is only clearing mark sheets of class 10th and class 12th.

If you are talking about getting admission in MBA, you have to take the necessary exams, /tests in the colleges you prefer. Different institutes have different exams such as CAT XAT MAH-CET. Anyone from any stream can pursue MBA. I hope, you are not talking about getting admission in some particular university/ institute.