You will probably want at least an i5 or better yet get a ryzen 5. I've never used OBS but when I stream my steam games from my i3 6100 computer to my main rig there are a lot of dropped frames and severe lag.
Yes. Minecraft isn't very demanding to begin with.
The 1500X will prove far better when recording and playing, the i5 may struggle a bit.
I've also got a better GPU in the system.
Yeah most definitely go with Chugalug_s build. It's got 4 cores and 8 threads like an i7 and the gtx 1060 will blow that 750ti or 1050ti out of the water.