Intel Core i3 6100 - RM 497
ASRock H110M-HDV - RM 245
Corsair 8GB DDR4 2133MHz Value RAM - RM 229
Gigabyte GTX1050Ti 4GB GDDR5 - RM 699
Seagate Barracuda 1TB HDD - RM 205
FSP Hexa+ 450W - RM 166
Tecware F3 - RM 125
BenQ GW2270 - RM 350
Logitech MK200 Wired Combo - RM 65

Total: RM 2581 (ETech price inclusive of GST)
Yes you can, you can go for i5 6402P to save even more, i5 6400 and 6402P have lower core clock speed (2.7GHz and 2.8GHz) compared to i5 6500's 3.2GHz, a top up of RM 50+ grants you another 0.5GHz pump so the performance/price ratio is definitely there for us to pick it over the other i5 models.

Yes you can (with top up of course  ), but you are strongly recommended to go for 8GB x 1 instead of 4GB x 2 for 8GB RAM because the mobo listed in the buidl list only got 2 RAM slots, meaning if you go 4GB x 2, you will have to sacrifice one of them if you want to add more RAM next time, or get a mobo with 4 RAM slots (this requires top up as well). And due to chipset limitation (H110/B150/H170/C232/C236), 2400MHz will be downclocked to 2133MHz automatically, so it is basically a value RAM speed but at a more expensive price tag.

Haswell is long obsoleted and Skylake is the successor to 4th gen (Haswell) and 5th gen (Broadwell) Intel CPU, no doubt that i5 6400 will edge out the i5 4460 in most of the aspects. Although the core clock speed of i5 4460 is higher than i5 6400 but it just doesn't worth my money considering it is an aged 22nm CPU and only supports DDR3 RAM.

To pick 4th gen over 6th gen, you need a LGA1150 mobo, this is a bit hard to find now especially LGA1151 has become the main Intel CPU socket since one year ago. Haswell only supports DDR3 based RAM, so you will need to switch to DDR3 RAM if you go for this path, the price of DDR3 and DDR4 is almost identical, so spending money in obsoleted DDR3 just doesn't look worth to me at all.