My opinion -
Q1 - If your long term goal is to be in India, prefer institutions within india. Reason - You won’t be able to build network, an imp component of any MBA program. I know someone who went Dublin and struggling even to get references back home. Adding A/B/C will help
Q2 - Target 720, you will land at a better place. GMAT is just a barrier, not the deciding criteria.
Q3- 2 years would be good considering your constraints and long term goals. If you can extend 1 more year, you’ll be eligible for IIMs 1 yr MBAs.
Overall - It’s my strong opinion that if you are targeting foreign MBAs, value derivation will happen only if you plan to stay, work abroad for few years. Financial burdens will be less plus you will something worthwhile to show. See the privilege of “foreign-returned” is slowly reducing in india as global roles are getting created here as well.