Recomended Memory and disks for the seServer (Odyssey)

Hi everybody,
I will be setting up a small home server with proxmox (virtual machine host) and then setting up Home Assistant, NAS and likely FlexOS virtual machines.

What memory modules would be recommended for this machine/board? I was thinking on buying just one 32 GB module, and buying another one sometime in the future when/if needed. Would using 1 channel slow this down? I do not know if the board and CPU would be actually needing both modules to be populated at once and getting advantage of this.

Hard drive SSD with M.2:
Similar question - does speed actually matters for this board? Will used controller and this Celeron CPU actually take advantage of drives which are faster/more expensive?

Thank you!

It is recommended that you buy enough at a time to avoid compatibility issues later. One is a single channel, there will be a little influence, and there will be no big difference in use.
The M.2 slot is PCIE3.0-X4, and an SSD faster than this is meaningless.