The i5-4570 has a slightly higher max turbo frequency than the 4460, so I would go with that.
However, the best choice would be to the the i5-4690K and a Z97 board, as it will allow overclocking which will allow you to play the most demanding games in Dolphin.
You'll need a stronger PSU anyways, at least 500 W to be on the minimum safe side.
As for the GPU, getting a dedicated GPU makes things easier in the long run. The R7 250 will suit you fine. Although I would recommend going the Nvidia GTX 750 Ti route, because Nvidia has better driver support.
However, the best choice would be to the the i5-4690K and a Z97 board, as it will allow overclocking which will allow you to play the most demanding games in Dolphin.
You'll need a stronger PSU anyways, at least 500 W to be on the minimum safe side.
As for the GPU, getting a dedicated GPU makes things easier in the long run. The R7 250 will suit you fine. Although I would recommend going the Nvidia GTX 750 Ti route, because Nvidia has better driver support.