• Integrated MSc and Normal MSc have the same value. The main difference is in case of separate MSc , that after BSc you have to apply for entrance examination and in case of Integrated MSc you have no need to sit for any entrance examination.
• No , there are no disadvantages in taking Integrated MSc after 12 since the course have all the curiculum of BSc and MSc but are fused in a way. So you will not face any problem.
• In Integrated MSc , the specialization and stuffs are dependent after the college/university. In general the specialization is done at the end of 5th or 6th semester.

I hope my answer helps you. All the very best for your future endeavors!