provided that RAID controller is supported, and your host have enough resources to let you install ESXi 5.5 U1 or higher, you should be OK. Please also make sure VSAN Networking needs are also met by appropriate physical NIC in your host.
yes ESXi needs to be residing on different storage than the one you are planning to use for VSAN storage.
min 3 hosts, per host at least 1 SSD and 1 HDD, supported raid controller (Passthrough mode is preffered but RAID 0 would do), at least 1 Gbps NIC for VSAN network
if your SSD are not detected by VMKernel as SSD then you will have to go through esxcli to mark device as SSD, if you are planning to do VSAN with vSphere 6, then this can be done using web client too.