SAP

A fresher in any SAP module have few openings. It is always good to get some experience in any of the modules, at the start you have to pay your dues as we say. Once you enter, then sky is the limit.

As you are a B.Sc CS student, SAP ABAB certifications will be a good option for you to become a SAP developer. After few years of experience, you may choose functional certifications to become a SAP consultant.

SAP certification is an exam conducted by SAP SE, the market leader in enterprise application software. SAP certifications help validate the expertise and experience of SAP partners, software users, customers and professionals who are looking to be placed in a SAP environment. The certification is recognized globally and is a standardized criterion for several roles and responsibilities.

It is not mandatory to have SAP certification. Decent graduation scores with banking domain knowledge and good accounting skills is a must. If you have good communication skills, it would be an asset.

Yes, you can act as consultant for financial companies by working under IT industry. SAP BI has great opportunities ahead.
You can check the below mentioned link:
https://www.shiksha.com/all-about-sap-applications-courses-article-5677-1

Both can be done, but if you want jobs in marketing stream, SD will be a better option. If you're interested into people management, then SAP HRM is better.
You can check the below mentioned link:
https://www.shiksha.com/all-about-sap-applications-courses-article-5677-1

SAP has its own partner institutions, which are expensive but highly valuable.
You can check the below mentioned link:
https://www.shiksha.com/all-about-sap-applications-courses-article-5677-1