Thank you all for your replies,
@sandesh, i did the same, jumped direct to the Absolute maximum rating section, but that was also bit confusing(as i said in my first post), anyway but now i have figured out what it basically says, thanks anyway for directing.
as far as the other questions, like how much current i expect to draw in my circuit, then the answer is, i m new to electronics, but good with microcontroller programming (as i m a software engineer), i m learning electronics, trying to make setup my environment for big project (like making a complete board, its bootloader, and operating system for that). that's why i have started with basic controllers so i can learn the basics quickly and then move to the higher controllers and bigger circuits.
Thanks all!