Greenify Pro allows you to hibernate system app which is usually greatest contributor to battery drain
Personally I find it pointless to use Greenify as is simply a half baked solution. If you really need to control battery drain you must root phone n install xposed mod cum greenify pro.
If you are worried about warranty than just don't root phone.
I have tested several battery drain control app without root n seriously all are just useless

color is very subjective...u should compare both side by side at samsung store..

you meant by build quality or interface wise? if interface wise, should be no problem and my Antutu can easily reach 50k everytime.
However, build quality wise, the home button do wiggle a bit

Thanks. Shall be arrive tomorrow, now at Sepang import clearance.