Hotel Management

The eligibility depends on the type of course that you wish to pursue, the details of some courses is stated below:
Diploma Class 10th pass from a recognised board with minimum 40% marks.
Bachelors Degree: Class 10+2 examination with at least 50% marks.
Post-graduation degree: Bachelors degree from a recognised university with at least 45% marks.
Graduate & PG programs may also require you to appear in entrance exams such as NCHMCT, AIMA UGAT, E-CHAT, etc.

Yes, hotel management has a good scope. Hotel management can include Hotel & Restaurant management, Cruise Ship Hotel management, Hospital Administration and Catering, Hotel and Tourism Associations, Airline Catering and Cabin Services, Club management, Forest Lodges, Guest Houses among others. Expansion of global travel industry and aviation industry is expected to boost hotel industry in next couple of years.

This course examines food processing systems and food quality management systems. Particular emphasis is on the principles of the various operations, such as freezing, chilling, drying, and canning, as well as on the application of Hazard Analysis Critical Control Point (HACCP) to food production with the aim of producing quality food that meets consumer expectations and the highest of hygiene and safety standards.

Kindly see the link:
http://goo.gl/BF0Ux7

Yes, if it is a good university you should go for it. Always target the top universities for better prospects. Here is a link which you can check to find out about the best universities for hotel management:
http://www.thebestschools.org/rankings/best-hospitality-degree-programs/

Aviation has a very little scope as of now. Hotel management is a better choice. In future you can also enter aviation industry with hotel management or hospitality management course. Aviation is not a bad field but growth and career opportunities are very few in this field. Rest both are interchangeable. With hotel management you can go into both the fields but aviation restricts its scope to its own field.

NIOS was established in Nov, 1989 as an autonomous organization in pursuance of national policy on education 1986 by the Ministry of Human Resource Development, Government of India. NIOS certificates are valid and recognized, and are accepted by all colleges/universities for admission.
All the best.