1- No software package for the MAC can do RAID 5. I use the HighPoint RocketRAID 2320 which does RAID's 0-1-5-10 from hardware. It is a PCI Express card and works great for me. I am using 4 x 500 GB SATA drives in a 2.0 TB RAID 0 for video.
2- MIrroring a boot drive will actally slow it down. Some have tried to RAID 0 a boot disk , but that can cause problems too. The best way to speed up a boot drive is to go with a 10K SATA drive as the boot drive.