Change the WD Red to WD Blue, it can save you RM 100, others are ok for your usage (get 8GB RAM if you multitask a lot).
Intel Core i3 6098P - RM 475
Asus H110M-K - RM 253
Corsair 8GB DDR4 2133MHz Value RAM - RM 229
Zotac GTX1050Ti 4GB GDDR5 Mini - RM 729
Kingston SSDNow UV400 120GB SSD - RM 203
Seagate Barracuda 1TB HDD - RM 219
FSP Hexa+ 550W - RM 188
Tecware Alpha - RM 229
BenQ GW2270 - RM 350
Logitech MK200 Wired Combo - RM 65

Total: RM 2940 (ETech price inclusive of GST)

If you prefer to run games at higher graphics settings, you can drop the SSD and opt for GTX1060 3GB.

1. Yes you can, that's the purpose of stock cooler on locked CPU.

2. i7 is overkill for your usage but if you have the budget then why not right? 

3. No need water cooling, air cooling is enough.

4. Personal preferences, by looking at the current trend (RGB and tempered glass), the 400R looks extremely expensive to me with its specs 
If gaming is the main priority, focus more on the GPU instead of CPU, upgrade the CPU to i5 and GPU to GTX1060 will give you a better performance than i7 + GTX1050Ti. This is because i5 + GTX1060 is a more balanced setup compared to i7 + GTX1050Ti (the i7 will somehow be "bottlenecked" by the GPU because the GPU is not fast enough).