Probably not. A home server would likely not get a high a number of simultaneous requests that can be processed in parallel. I suspect that fewer more powerful cores would lead to higher performance in that particular case.

If you can service fs calls on multiple cores, yes. The processing stack for a network fileysystems server is TCP or udp load, fs load and asynchronous clients. If it's just you, a couple of core does it. If it's you, your partner, a home pvr using network file streaming, kids playing music, I could believe some parallelism would help.

Big memory for zfs arc would help too.

Yes if you put your services into VMs.