2 ways to get WiFi connection on the PC.

First way is get a mITX mobo with on-board WiFi card, second way is get a normal mobo and USB/PCIe WiFi adapter. First solution is more expensive but you can build a small rig like console/mini PC (vital for space-saving), second solution is cheaper in overall bu can be bulky in size.

I prefer first solution since no gaming involved, thus no clearance issue on GPU (no need to get dedicated GPU) especially when building a SFF rig.

Intel Core i3 6100 - RM 467
Gigabyte H170N-WiFi - RM 536
Kingston 8GB DDR4 2133MHz Value RAM - RM 147
Kingston SSDNow UV400 120GB SSD - RM 153
WD Blue 1TB HDD - RM 209
FSP Hexa+ 400W - RM 145
CM Elite 110 - RM 159
Acer R241Y IPS - RM 622

Total: RM 2438 (ETech price inclusive of GST)

Torrenting and watching movies on i3 is totally fine, Skylake i3 is very powerful and comparable to 2nd (or even 3rd gen) i5