I'd like to know how largest each HDD and how largest whole HDDs a raid controller card can support?
what factors restrict capacity of one HDD it support and which factors restrict capacity of all HDDs it support?
The major restriction factor is the firmware of the controller so it all depends on the controller only. Some old controllers don't know how to respond to drives over 1TB so a simple firmware upgrade (if available) usually can fix this issue.
You'd need EFI support to boot partitions larger than 2TiB, so the 2TiB is still a major barrier for x86 PCs. Some motherboard with EFI BIOS support were announced, not sure if they have been released into the wild.