Most gaming laptops have hybrid solutions and thus usually automatically switch to the integrated GPU on battery. Thus, you will have plenty of battery life, you will just have extremely low performance in comparison to a 660, 675m, 675mx, 7970m, or 680m on battery.
🙂
It is completely correct that the MSI I listed above does not have an OS.
However, students usually have methods to legally purchase operating systems for VERY cheap.
Microsoft offers extremely low educational prices for college students, and thus paying for retail or even OEM pricing is not really recommended.
http

/www.microsoft.com/education/en-us/buy/Pages/eligible.aspx