A) If you mean to partition before setting up the RAID, I have never heard of a RAID controller that will eat partitions instead of whole drives. Community, please enlighten me if I have missed a common practice.
B) Hmm. 4 GB of total disk space, 1 GB of the RAID used, 3 GB of the RAID free - you are doing a 4-drive RAID0, yes? Please do regular backups, since the loss of one drive, or the RAID controller, means the loss of all data.