First, why would you spend money on servers that you don't understand the capabilities of?!
Yes, you can use HP's software to aggregate the links. If you switch supports LACP you can get 4Gbps bi-directional. Or you can get link redundancy. Or you can use each port individually. Or a combination of the above.
The dedicated management port is primarily for environments where the primary NICs are sensitive to management traffic, or your switch/environment doesn't support vLANs. iLO can be accessed through either the dedicated management port; or it can share it's connection with the first on-board NIC using vLAN tagging.
The best way to RAID 4 drives will depend on what you want from them. RAID10 is faster for some situations; RAID5 will give you more storage space.