Transferring School BS-->MS. Will i need new F-1 visa

[Rastignac]

So I just finished my BS from a US university. My F-1 Visa is valid for another year. I am going to pursue an MS. I have already obtained the new i-20. The problem is, my current visa does not cover the entire duration of my MS program (expires around 6 months before program end date). 

 I wish to be able to travel to india in the interim period and during the following OPT period.

 

So what should I do. I have been told that i will be able to travel back to the US now with my valid visa from old institution and new i20. 

but should i get a new stamp anyway (with extended validity for program duration + OPT?)

 

what are my chances of getting that given that my visa is still valid?

 

should I do it now or later (maybe december?).

Should i apply here in india or canada (i live fairly close)

 

also it appears i wont qualify for the dropbox program (due to changing schools) - am i right?

 

thanks!