if you're intending to do any actual work the CPU you buy will have at least 6 cores/12 threads so there's no choice to make between single and multi-core CPUs I've got a 10900k and a 5950x on the desk in front of me and in practical terms there's sod all difference between them unless you're doing something intensive and…
Multi GPU doesn't have much support like it used to. You're best bet is sticking to just the 1 graphics card for compatibility and simplicity's sake. VRAM is good for stuffing large or many textures into a scene and for large buffers (for 4K screens), and a decent amount should be required even for rendering offline, note…