The HD3000 intergrated graphic on sandybridge is enough for office suits and internet. Game you mentioned shouldn't be problem.
If you like to keep large number of webpages open and keep webbrowser running for day at a time then having a large memory 4Gb+ is very recommanded,
option 1 is better then 2 cause for the same price i5 2410 is faster and have turbo.
I am against netbooks because I can't stand slow computer. not going to recommand no6
540M is about twice as good as 520m. I know it can handle a average game.
but i'll use it mainly without ac adaptor which will force the laptop to be in optimus with onboard graphic to save battery on most times. so the advantage of both 540 and 520 is not that much without ac power. is it correct?
also what's the advantage of 520 M over intel hd of i3? i mean in gaming power?