Building Plex Server - Questions - Processor?

[Vectraat]

So I have a NAS and I'm thinking on buying a NUC or some other kind of mini-PC and using it as my Plex Sever/Media Playback Device for transcoding and keeping the NAS as storage because it has a shitty Intel Celeron (Synology DS918+).

1.) I haven't been following all the drama surrounding Spectre/Meltdown, but I can see from the Plex website to do a single 4K transcode you need an Intel Core i7 3.2 GHz processor. So I was looking at an 8th Gen Core i7 8700K 3.70 GHz. What I'm wondering....

a.) I recall reading that Intel had planned to release processors later this year free from those vulnerabilities. Not sure if that's entirely true or they're just patching them over. Does anyone know if those processors are here yet or when they will be? If I'm spending this kinda money on a processor, I'm not interested in paying for a dip in performance. (At least that's my understanding of what would happen when those vulnerabilities are patched).

b.) Is it a bad idea to go with a mini-Computer like a NUC/Brix etc., as a Plex Server? I imagine It's going to get very toasty if I'm trascoding 4K. I kinda don't want a giant tower in my living room. If this won't work, what would you guys suggest for a media player + Plex Server for transcoding?