Yes you can use your GPU, and you can't use that CPU with that motherboard most likely unless it had an update pre-applied to allow you to use a Kaby Lake processor. And if you need that update you need a compatable CPU first (thats supported, so not that G4600) to update the motherboard so you can use the Kaby Lake. Your best bet is to return that motherboard and buy a B250 motherboard which natively supports Kaby Lake processors like this one.
https://pcpartpicker.com/product/JNH48d/msi-b250m-pro-vd-micro-atx-lga1151-motherboard-b250m-pro-vd
Oh and lastly concerning 4gb, it's low RAM wise, so it depends on what your games your playing as to whether or not you encouter issues. The GTX 560 and 4gb of RAM will be a bottleneck though. The goal should be 16gb of ram, though you can get by with 8gb right now and the 1050 ti. If money is tight use PCPartPicker to help select a new motherboard with 4 ram slots and upgrade as funds allow you to.