M.Com

Yes, you can do
Yes, you are eligible to join the M.Com course after completion of the B.Com course. Each and every university will conduct its own Entrance Exam to give admission for the M.Com course. As you are telling me that you have not got through the Entrance Exam, it is better to join this M.Com course in private mode or distance learning.

Yes, you can do Ph.D after doing a Masters degree from correspondence. You can also give a net exam, so that you will get admission in a good university.

Course/Duration/Fees
Bachelor of Commerce [B.Com]/3 year (s/)17,565
Master of Commerce [M.Com]/2 year (s)/12,010
Bachelor of Arts [BA]/3 year (s)/17,565
Master of Arts [MA]/2 year (s)/13,256.

Himachal Pradesh University, Shimla Fee Structure and List of Courses Summary
Course/Duration/Fees
Bachelor of Hotel Management [BHM]/3 year (s)/1,80,000
Master of Commerce [M.Com/2 year (s)/440
Master of Philosophy [M.Phil]/1 year (s)/16,517
Master of Science [M.Sc]/1 year (s)/640.

List of Rajasthan University Fee Structure:
Courses/Fees/Duration
Master of Arts [M.A]/3,285/year/2 Years
Master of Science [M.Sc]/3,285/year/2 Years
Master of Technology [M.Tech]/72,000/year/2 Years
Master of Commerce [M.Com]/3,285/year/2 Years.

It is possible to study CA along with job.
To become CA, first, you have to CPT exam and then following exams like IPCC.

Hi. Yes you are eligible for PSTET. For details information you can see below link
https://www.shiksha.com/exams/pstet-exam
Thanks.

M.Com course fee at Panjab University, Chandigarh is INR 8,707 per annum. The course fee for all the specializations of B.Sc is INR 60,390 per annum. https://www.shiksha.com/accounting-commerce/course/m-com-hons-panjab-university-Chandigarh-271111
You can hit the link for more official updates.

Top M.Com Colleges in Mumbai - List of M.Com Colleges in MumbaiManipal University, [MU] Manipal. KJ Somaiya College of Arts and Commerce, Mumbai. KPB Hinduja College of Commerce, Mumbai. Guru Nanak College of Arts Science and Commerce, [GNCASC] Mumbai. L. S. Raheja College of Arts & Commerce, [LSRCA] Mumbai.

Bachelor of Library and Information Science [B. Lib. I. Sc]3 year (s) 36,000
Bachelor of Performing Arts [BPA]3 year (s) 36,900
Bachelor of Social Work [BSW]3 year (s) 36,000
Master of Arts [MA]2 year (s) 564.