Pure Nvme first time build moving from Synology NAS

[cbruiners]

I'm looking at building a pure NVMe NAS box for power home use and I'm a little torn on the direction of travel (including TrueNas Core or Scale):

• Case: Fractal Design Torrent Nano (looked at rack mounted, but wanted something thats aesthetically a little more pleasing)
• Motherboard make and model: Still looking for the MB with the most NVMe PCI M2 slots (seems limited to 2 on mitx case)
• CPU make and model: Core i5 or i7
• RAM quantity: 64GB+
• Hard drives (pure NVMe PCI M2): Crucial P3 Plus 4TB CT4000P3PSSD8 or Samsung Evo 2TB drives
• Network cards: iTX seems limited to 2.5Gbe, but might find a 10Gbe NIC
• GPU: TBC depending on space inside the case and vs 10Gbe network card

My use case is:

• 90% of the time streaming video including 4k video across a Netgear Orbi wifi setup (this works fine at present with my Synology NAS) to multiple devices (some are wired up rather than over wifi, but transcoding is critical server side using plex).
• Run VM's / docker containers, ones I spin up and tear down, for testing purposes.
• Though the network speed is limiting the NVMe performance, I'd rather future proof and then replace the motherboard later on when the speed has caught up, have NAS HD's in my Synology but lost both drives and killed all my data, hence moving to solid state which has better life spans.
• Loved love to hit close the 1Gb per second across the network (wired), though I know I need a 10Gbe card to do that.

My questions are:

• I suspect I need TrueNas Scale over Core, as I want to be able to run containers / VM's?
• Anything wrong with the setup I'm looking at building?
• Is a Core i5 enough video considering its Core i7's that have transcoding capabilities? Thinking of my Plex user case
• Are the only 10Gbe cards avaialble in PCI-E? Thinking its a trade off between the GPU and upgrading my network card :(
• Do you know of a mITX that has 10Gb?
• I keep reading I can't just keep adding HD / SSD space as I grow; I have 6TB of data that I need to back up and my plan was as NVMe's grow from 4TB to 8TB that I would replace them with larger storage. Is this not possible?
• My Synology NAS' have been super reliable (HD that haven't been); does TrueNAS fall over alot (reading the Forums it seems not uncommon of lost data)

Its my first time setting up a TrueNAS NAS, so any tips much appreciated and moving from a Synology (which is easy) makes this feel more daunting than I suspect it really is.