The PSU is the standard 320W
even if you get a very low power graphics card,I think the GeForce 1050 TI will work
you should pretty easily be able to measure the PSU and compare it's dimensions and available cables to any possible replacement to ensure compatibility.you can't really change the PSU out easily, since it's "proprietary".
PCIe power cables; usually 6 or 8-pin, to power the GPU.I'm not sure what you mean by "to find out if it has the proper power cables"