for question 1 & 2
The dorado v6 can support NVMe SSD disks or SAS SSD disks. But can't support NVMe + SAS at the same storage. also full support dedupe and compression on dorado v6.
the following dorado v6 support use NVMe or SAS disks:
3000 v6, 5000 v6, 6000 v6,8000 v6,18000 v6
5300 v6, 5500 v6 ,5600 v6, 6800 v6, 18500 v6, 18800 v6
for question 3
huawei non flash storage support auto tiering on three or two different type of disks. but on dorado storage it only have SSD disks. so not need auto tiering.
for more information please refer the below link:
http://support-it.huawei.com/storage/#/home