MCA

HNB University is a central government university. In my point of view, you can opt for it.

It all depends on you. If you want to study further then go for MCA, it will boost your career.

If you want to join a IT company or IT-Infrastructure wing of any MNC than MCA is best option. If you want to go in teaching/research field than M.Sc is better option.

After B.Com, first priority is M.Com. If you are not interested in that, you can go for MBA. Otherwise, if you have interest in computer programming, coding, developing, then you can choose MCA!
Good luck!

If you MCA from a prestigious university with excellent track record of campus placement then you have high probability of getting job in MNC. Starting salary of MCA grads varies from 3.5 to 10 Lakhs per annum depending on ranking of Universities and hiring company. High end salaries are offered by companies such as Google etc.

If you had maths as a subject in 10+2 stage then you are eligible to seek admission in MCA. With extra effort, you will be able to cope up with MCA studies. MCA is the second best educational qualification after B.Tech CS/IT to seek developer or tester job in IT and ITES companies.

According to me, both are similar. The difference is that
1) B.Tech is 4 years. MCA+BCA will be 5 or 6 years depending on lateral entry.
2) You will find MCA as better because the syllabus will be moderate. Whereas B.Tech will be hectic.
3) Finally, you can do M.Tech in CS after MCA and also after B.Tech.
So, think about all these points taken and then decide.

Yes, you can. You would have applied for state entrance examination before. But since you had not gone for any test, you can apply for particular colleges, as some college provide direct admission.