This is not possible because the stock VirtualDSM kernel has no virtiofs module (like Xpenology has).
Yes.. See https://github.com/vdsm/virtual-dsm#how-do-i-add-multiple-disks
You cannot expose SATA controllers. You can either just bind a folder, where a virtual disk image (data.img) will be created, or passthrough a whole block device (not recommended). See https://github.com/vdsm/virtual-dsm#how-do-i-change-the-location-of-the-virtual-disk
You cannot expose a NIC. But like @JuanjOD already explained, you can create a macvlan network. See https://github.com/vdsm/virtual-dsm#how-do-i-assign-an-individual-ip-address-to-the-container
Yes it is always safe to upgrade. Because this container uses a completely stock (unmodified) version of DSM, which means that upgrades can never break the system. With XPenology that is different, because it modifies a lot of things (bootloader, kernel modules, etc).
Also this update should fix the problem with notifications that you had (see https://github.com/vdsm/virtual-dsm/issues/313#issuecomment-1788824213 ).
For all other people: I wont be replying here anymore. Because almost every question was already answered in the FAQ.
If you have any issue, it should be reported to https://github.com/vdsm/virtual-dsm/issues and not here.