Programming Languages

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

Data structure is nowhere bound to C programming. It is a concept of storing, and manipulating using some techniques. You need to learn those data structure using any of your favourite language. You can also prefer some standard books.

Yes BTech will never die if students are sincere. Be perfect in your stream and BTech is the best way to get nice jobs around

This question is nothing to do with calling C+ private protected because of public use. Learn C+ and it is a good language to prefer over C and understand OOPS concepts.

Expertise of C+ is must for all field of engineering. Based on C+ expertise, you can learn any other programming languages easily. In addition expertise on any RDBMS and statistical tools will help you in MS data analysis.

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.

You can learn Python, R as they are most widely used programming languages for data science. You can also learn Apache hadoop and distributed computing techniques.

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