Yup, it is sufficient, but try not to expect too much from it since its a budget notebook after all 

Sure can haha, it may be a budgeted notebook, but those are pretty simple stuffs 
When I said don't expect too much, it means try not to expect fast rendering/simulation of softwares or more demanding games 
Still, shouldn't the newer versions of notebooks be powered by B960 already?

Yeah, you can add the RAM if you want, would help a bit in multitasking, but 4GB is pretty good already to be honest

May I ask why you need 15"? With same resolution, you are seeing more or less the same picture as in 14" though

With your RM1.2k budget, you could go for sandy bridge i3, which run photoshop much better than Pentium B8/9xx.

Acer
E1-471-32322G50L, i3-2328M + Intel HD3000@RM1299, 2GB, 500GB, Linux
Fujitsu
LH531-MYE0100348, i3-2350M + Intel HD 3000@RM1299, color: red, freeDOS
HP
1000-1201TX, i3-2328M + Intel HD3000@RM1299, 2GB, 500GB, freeDOS, no USB3.0
Lenovo
G480, i3-2328M + Intel HD3000@RM1299, 2GB, 500GB (5400rpm), FreeDOS

Usually a 14" mainsteam notebook would be a better pick because of the better performance. but since you are more interested in portability, the S300 will do
It can handle the stuffs you mentioned, but try not to expect too much in Photoshop, especially more intensive tasks 

The latest S300 model comes with W8 already right?
It should be able to handle your requirements, but on the safe side, try to "test-drive" on display models, just to be sure 

Yup, I've seen display units there the last time I went there

Well, they are display units (which are meant for you to abuse try)