thinking about buying a Vaio EA and need some advice

this is the model that i configured:

after 10% off student discount and taxes being added, pricing is:
962 .98

this is what i will be doing w/ my laptop:

• school work
• photoshop/editing photos
• possibly light gaming, im not a serious gamer who plays the latest games but maybe i can play some older popular games

I have a few questions about my configuration.

1. The resolution is fine for me but is the screen pretty good for amateur photo editing? i went to best buy to look at an i3 Ea w/ ati card and its hard to judge the screen in a bright store since im not able to adjust screen settings
2. is the HD easy to change out? i plan on adding a 7200 rpm drive i have at home and possibly an SSD drive in the near future
3. i chose 4 gigs of ram, 6 gigs is 150.00 extra, for my needs is 4gigs more than enough? and are ram upgrades easy on sony vaios?
4. are sony warranties worth the money? whats the forums opinion about sony reliability
5. im content w/ 3.5 hrs of battery life, should i expect this number to be accurate or will i be prob getting less during normal usage? should i upgrade to a larger battery for 100.00? i dont want the battery to stick out of the machine any farther than the regular battery..should i just wait to buy a third party battery for cheaper on ebay?

finally is this a good deal? (i just bought an HP dm4 and hated the touchpad but the touchpad seems decent on the sony)