Check the power specs for your monitor at the Dell website. There are many. many Dell monitors.
No
To save power
eat it
Hibernate is a power mode that allows the computer to save an image of the desktop to the hard drive and enter a state of reduced power consumption to save energy.
turn off power save mode
Control Panel --> Power Options
You can do it from Power Option in Control Panel.
The battery life on a Dell Inspiron 6400, 9 cell battery can last anything from 3h30mins to 5h30mins. The mainly depends on how the power saving mode has been set, when you reduce the computer's performance you save battery life.
70%
Hibernate.
That means your computer has entered a state of Hibernation to conserve battery life. Very useful if you're working on something at work or school, and you want to resume the progress at home.