TYPICAL gaming should rarely exceed 250W total for that PC assuming no overclocking. Roughly 125W for CPU + mobo etc and roughly same for that graphics card under load.
CPU should actually be lower as that's more of an all-cores load amount. Anyway, no point getting specific as it's way under the PSU's output which should exceed 550W peak.
I doubt you need any PCIe connectors in addition (would be odd for a 550W since you probably only need a single 6-pin, 2x6-pin or 1x8-pin... if for some reason you needed more you can get MOLEX adapters that would work fine as the 12V power still comes from the same source.
Other:
*I'd get a 3000MHz kit of DDR4 memory with CL16 (or lower CL). I guess the R5-1600 is a lot cheaper? If not I'd get the R5-2600 as it's better at out-of-box compatibility with the memory and keeping higher clocks.
3GB is kind of borderline though now. I know a budget is a budget but if you can get higher I recommend it... there may even be some reasonably priced NAVI options coming but I can understand not wanting to wait.
But typically if the game wants more than 3GB you end up with big stutters at times when the game stops to SWAP data between system memory and video memory (hopefully not back to an HDD though I think that can happen).
RX-570 4GB and GTX1060 3GB cards are roughly the same performance, but RX-570 has more VRAM and the cost where you are compares how?
https://www.techpowerup.com/reviews/Sapphire/RX_570_Pulse/30.html
There's more to NVidia vs AMD but that's not for this post.
But when I checked USA prices quickly I saw some RX-580 8GB cards for the same cost as the GTX1060 3GB cards at roughly $200USD.