If your gaming is really light, mostly casual and not graphic demanding, then no need to spend money on dedicated GPU, the iGPU of Skylake CPU is enough.

Intel Core i5 6400 - RM 828
Gigabyte H110M-DS2 - RM 290
Corsair 8GB DDR4 2133MHz Value RAM - RM 200
Kingston HyperX Fury 240GB SSD - RM 385
FSP Hexa+ 400W - RM 149
Thermaltake Versa H25 - RM 170

Total: RM 2022 (Techview price inclusive of GST)

Last gen CPU price is almost similar with current gen, so not worth to downgrade, some minor adjustments to the build will do.

Intel Core i5 6400 - RM 828
Gigabyte H110M-DS2 - RM 289
Kingston 8GB DDR4 2133MHz Value RAM - RM 196
Zotac GTX750Ti 2GB GDDR5 ZT-70605-10M - RM 509
Kingston HyperX Fury 120GB SSD - RM 209
FSP Hexa+ 400W - RM 145
Bitfenix Nova - RM 149

Total: RM 2325 (Techview price inclusive of GST)

Swap the PSU to 550W (RM 188) one if you are going to upgrade or add more hardware to the rig in the future so you don't have to change PSU next time.

Edit: GTX560 and 750Ti is very close in performance, if you can reuse then it would be great and save a lot of money.

You still have your old PC with you? If yes, then is the mobo available to reuse? If no then new LGA1155 mobo is quite hard to find nowadays 

If you go for Skylake (6th gen) system, the iGPU of Skylake is quite powerful and is able to handle casual gaming (stronger than GT730, almost equivalent to GT740/R7 250) so you can skip the GPU (save money  )

It's all depend on you, if you are ok with current screen size and resolution, then just stick with current monitor.

As long as your monitor has at least a display input, it can be paired with any modern GPU either via direct connection (e.g. HDMI to HDMI) or converter (e.g. HDMI to DVI).
CM Elite 110 and Silverstone SG13 are mITX form factor, not mATX (you mentioned you want to build mATX).

mITX mobo is expensive, expect > RM 500 but it comes with internal WiFi card so you don't have to spend extra money to get WiFi card/adapter.

HD 530 is around 75% faster than HD 510.

Don't think you can any new mITX mobo for your i5 2500 now, so maybe you can sell it off and add the funds into your budget.

If light usage then Core i3 is enough.

Intel Core i3 6100 + Gigabyte H170N-WiFi + 8GB DDR4 RAM + 1TB HDD (if needed) + FSP Hexa+ 400W + mITX case of your choice, the estimated total price is around 1.5k+.

If you want modular PSU then you need to add another RM 200+/-, if you go with Silverstone mITX case, you might need SFX PSU which is even more expensive, if you pick CM Elite 110 then you can go for Seasonic M12II EVO series or Superflower Leadex.

FSP modular at RM 200+? You mean Hyper M? It is semi modular, not fully though.