Let me answer your questions one by one.
1. sun certification is a program in java technology which covers the today's software development trends and the enterprise architecture. You can either join one of the partners of Sun in India or can prepare on your own. In both cases you have to appear for the certification test. So in the end knowledge matters.
2. As I think till now you have not started learning java, so for you it will be Sun Certified Java Associate(SCJA). What this particular module covers can be found on their website.
3. Exam fee will be around Rs.15000
4. A lot depends on you, so i cannot answer that question straight. In my opinion it is not that tough but genrally people prefer an easy language over the one which is a bit hard without considering the benefits of the technology. It is the most reliable programming language there is. Its worth learning and you will definately stand out of the crowd, if you know how to code in java.
5. As a fresher you will be getting the same as for any other language but with your work and experience it can do wonders.
6. Java is going to last for a long long time. I have seen a lot of programming languages come and go but java has always been there in the industry and so will be the future. Reasons for that is because java has a very strong architecture, support, and has been constantly changing and improving with the needs of the industry. so you are not making a mistake if you are opting for java, your career is very much secure than it will be in any other technology.
I hope that will help you a bit making your decision. Have a nice day ahead. take care. bye