Buying Advice for a mini itx budget HACKINTOSH

[Kazbah]

i5 with built-in graphics will perform better than the i3 for sure (you can always add a GPU at a later time)
You would have to use the HDMI or DVI ports on the motherboard to connect the display. That USB Type-C connector acts as a USB 3.0 port (just a different form factor).. it does not act as a Thunderbolt/Display port.