I've read on the product details that the card can support 32 drives. How it can do that with its 4 port connector? Is it possible to connect more than 4 drives on that single connector?
The technology is called SAS Expander. So you would need a supported expander box for additional disks and the requiered cabling.
According to pictures and docs, the card has one internal SFF-8087 port (seems there is no cabling included). There are SFF-8087 to SFF-8087 cables for connecting disk boxes and there are SFF-8087 to SATA fan-out cables.
In an expander situation, you would be limited to 6 Gbit/s bandwith per port.
Can it handle more arrays on that 4 port? Is each single port represented by a different RAID array? I mean a RAID 10 and a RAID 5 simultaneously.
I don't know that card. Usually, any disk connected to a card can be assigned to a RAID group defining a RAID level. Also usually you are allowed to create different logical volumes (disks) on any RAID group.
You should really consider buying the mentioned «Optional battery backup unit (direct attach)» as most RAID cards are not caching writes whithout it and ESXi will also not cache itself.
