Accounting & Commerce

CMA means cost and management accounting. If you pursue it in India, it is recognised as CMA but if you pursue it from London, it is recognised as CIMA. CIMA gives you global recognition as certified in management accountant. The next difference is the syllabus. You can get all the details such as syllabus and its procedure from its website of ICMAI/CIMA, London. In India, some training institutes such as IMS pro school also offers CIMA.

Free online courses will not help you or add any value in your C.V.
However few training institutes such as:
a)Edupristine
b)EduCBA offers online courses in India. They will certify you with:
a)BSE/NSE
b)CPA(USA)
c)CIMA London
d)ACCA
You can get prepared for their exams or get certified for short terms only. Follow their respective websites to get more details.

Definitely age matters for freshers to get a job either in private or government sector. You should complete ICWAI before the age of 30 i.e. all levels of CMA. Few companies hires after the age of 30 with the valuable experience of around 2 to 3 years. You can follow the websites of ICMAI/placements to get more details such as rules and procedure.

For CPA, you can pursue it after M.Com. However, it's a short duration course. To get a job, you should finish your study before the age of 30. Good companies either in private or government sector hire the freshers below the age of 30. So, if you can, then pursue a) CMA, b) CFA, c) CPA. You can follow the respective websites for the details such as admission and the procedure.

Definitely you can. You must pursue PGDCA (one year). Make sure to check the official website of Aptec for complete details.