Is there any particular college that you wish to apply. See, apart from the NITs, state wise run colleges will have different parameters so it is not correct to even generalise. If you let us know the colleges you are interested in or even the state where you are studying, we could help better. For the NITs, there is NIMCET and I would advise to apply for it if your BCA is recognised.

Yes, You can apply for postgraduation programm, only Your Graduation should be completed from a recognized Institute. For MCA programme if you are targeting NITs then the exam you need to appear NIMCET. As per the eligibility you should have minimum 60% in your Graduation as a General Category. To check the complete Eligibility of NIMCET you can go through with the given below link.

NIMCET Eligibility