Full Time

It's always best to go for a regular degree (as compared to a correspondence course) whenever the option is available. Let's look at your dilemma in two parts for a holistic reasoning: (I) Whether to opt for getting a Bachelor's degree at all? (ii) Regular vs. Correspondence
Even though one can do without opting for a Bachelors at all if one is pursuing CA I suggest one should still obtain the degree for three reasons -
1. There is no guarantee one will clear all the CA exams in the first attempt (though I hope you do). You won't have any degree against your name to speak of till then. To me, that's a scary thought.
2. Till one doesn't clear all the exams, one's chances of employment decrease in a lot of places. Most places, actually, even if you've cleared IPCC.
3. You won't be able to go for higher studies because you are not the equivalent of a graduate till you clear your Finals. Now, let's look at the dilemma of a Regular vs. Correspondence course -
Academically, in a correspondence course, you will: (a) Not have direct contact with any college faculty. Even if you take private tuition, it's not the same as going to a college and studying under a professor.

It is possible to pursue 2 courses together. However, one has to decide which course to pursue as a regular mode of learning and which from distance / correspondence. There is difference in Correspondence and Regular course; I would say it varies from one subject to the other also from one degree to the other. However, in general a course through distance learning does not have as much value as the regular one. So, if you can do a regular course, it would hold a lot of importance and thus be a much better option. The acceptability and recognition of a full time course is higher in industry and the long term career gains are good. Correspondence courses are ideally meant for those who are working and cannot leave their jobs to further their education. It is only to leverage ones experience and not so much as a stand-alone degree. The employ-ability of a full time degree holder is the most and those with a distance education degree may face a drawback as far as employment options with MNCs are concerned. However, what is also relevant is your experience; skills and profile should match the profile needed for the job and organization. Thus, it would be best for you to pursue a full time course.