Java

Being a B.Com graduate with a Diploma in java, I expect a minimum of 10k per month. Assuming you have a very good knowledge in java, you can jump up to 40k in an year or so.

Advanced java is something which makes an application. Start learning advanced java, and platforms like hibernate, spring, bean, etc.

I would have preferred Mindscripts and Aptech after that.

You can learn it online, if you have experience of some languages like C+ or C. You can refer to the material online and practice yourself. You can also prefer some professional institutes to prepare you for Java certifications.

SSI Education is famous in Indore for technical studies.
You can visit the below mentioned link:
http://ssiedu.in/java-training.html

It is excellent to see your eagerness in learning Java. Java is a great step towards CS. For a certification course, I would highly recommend the OCAJP or the Oracle Java Associate available for both Java SE7 and Java SE8.
For study material, you can first go through The Complete Reference written by Herbert Schildt.
Hub4Tech is the best institute for Java training.

Yes, java has wide scope. You can apply for various jobs, if you learn java. You can go for android or advance java.

Java is quite in demand and it's ever growing. So, I would definitely suggest you to go with Java.

It depends on your interest. If you are not biased you should learn Java.