MCA

BCA 1st and 2nd year syllabus is equal with MCA entrance syllabus.
You have to practice mathematics 14 hours in a day. To crack MCA entrance, you need a depth concept about mathematics. Integration, polynomial, matrices, discrete mathematic, provability and geometrics part. You need to practice programming language like C, C+, networking, PC-software part.
Below mentioned are the top institutions:
1. NIT.
2. IITs.
3. LPU.
4. Jadavpur University.
5. Techno India.
6. MCKV, etc.

It will be difficult to get job abroad without experience. You are advised to gain few years of experience to fulfill you dream of working in Dubai.

Yes, you can pursue MCA in 20,000 rupees.
For for fee structure and more details, check out the below-mentioned link:
http://www.ignou.ac.in/ignou/aboutignou/school/socis/programmes/detail/174/2

B.Sc (CS) is degree programme of three years but is also of four years in some universities. MCA is a post graduation course of two years duration. In all you can complete both the courses in 5 to 6 years duration.

No, MCA require 10+2+3 Bachelor degree with mathematics or equivalent and 60% aggregate marks for application for MCA. After that you have to pass an entrance exam PGCET, JECA, etc. after fulfill all criteria, you can get admission to MCA.

There is a lots of chance for white hacker. Cyber security is the most booming area nowadays. So, it is a better opportunity to start career. You can work as VAPT, participate in bug bounty, do CEH of entry level to pass for all. Side by side, you can complete your Master's degree.

In Pune, Arizona Infotech is a good institute for Security course like CEH, CHFI, ECSA, etc. There is no need but doing it is always better.