Using a HBA card for virtual NAS

Just bought a LSI 9200-8e and I think that I have all the hardware correct, just a few questions on the software side of things:

• Should I pass through the entire card to a truenas vm or each drive individually (my gut says to passthrough card as to increase simplicity)?
• If I wanted to increase my capacity in the future can I just by a card with more sas lanes and plug the drives into it, the ZFS wouldn't get corrupted?

On the issue of corrupted data: while I do have backups, I have a few questions on easly avoided data loss:

• Do I turn on/off the host vm or the DAS first?
• What risk is present if the power goes out and the UPS runs out and both machines are shut off at the same time?

I am running XCP-NG if that matters at all.

Thanks in advance