I need help building a gaming PC.

I'm planning to buy a PC but i'm unsure of what GPU i should purchase. I intend to play games like SMITE, Overwatch, maybe Witcher 3 and the new incoming Quake game. My original list is : 500GB HDD Toshiba 32MB Sata3 7200 RPM ||| 120GB SSD Kingston Fury Sata3 ||| GeForce GTX 1050 TI DDR5 OC 4GB GPU ||| Intel Core I5 7600 3.50-4.1GhZ 6MB CPU ||| ASUS H110M-R LGA1151 DD4 Motherboard ||| 2X 4096 MB DDR4 2400MHZ RAM ||| 500W Peak PSU

But meanwhile a friend of mine said that my GPU would cause my PC to bottleneck, so he recommended me a Radeon R9 380 4GB DDR5 GPU. I'm not good at hardware at all, so I was wondering what you guys think. My budget can't be very high, my original budget was around 780€, going up to 830€+ if I choose the Radeon GPU.

First question : Will the Geforce 1050 ti 4gb gpu cause my pc to bottleneck? Should I go with the radeon r9 380 4gb GPU or do you guys recommend a different one?

Second question : Should I get 2x 4096 MB DDR4 RAM sticks or just 1x 8192 MB DD4 RAM stick?