There're 2 choices of the lights, one is 4 inch , one is 6inch.
If there is a room around 100sf - 150sf , you will need 4inch x 4.
If you prefer brighter, you may select 6inch x 4 ( really bright as it suitable for a family gather at living room).
if you are using 6inch light, you may choose to only switch on 2 lights at one time to save electric bill.
Note: The estimation above are for 9ft wall
4000K(a.k.a cool white) is a bit yellowish, but it depends on your wall color and ceiling color.
The more yellowish your wall, the more yellowish the light is.
If your wall is white, you wont feel too much difference with white color.

I don't suggest you take 6000K as the light is too bright, everything will become grey+blue color instead of showing the actual item color. For example, your wall is white color, but the light will cause it looks like kinda grey+blue, the color became not really natural.

4000k light can read newspaper or not?

my gf hates 3500k. she only allows me to use 6000k led

I saw a lot of people bought 6000K LED lights from houses lighting.
I wonder how they tahan? 

Now Phillips 4" are selling at 24.90 at pudu and 29.90 in puchong the shop beside house of light, do you ask think any chance is fake Phillips??