Regarding the first one - Yes, that would be the Mellanox driver for all Mellanox cards (one driver fits all ;-)
Regarding the seconds one - that is i guess a general term to represent all kind of HW offload engines. if that is so… then you need to understand that the HW is doing most of the offloading work (and the driver supports that).
Since you have a relatively old card, some of the offload functions may not be available but i am sure some others will work and you will notice the benefit. give it a try.
With the next Mellanox HCA generation (ConnectX/2/3) all modern staff is there, out of the box.
UPGRADE! seriously…! youll save yourself ALOT of mind bending bother by upgrading to ConnectX2…
try to avoid older cards especially CX4 cards as the connectors break of the PCB. you can get them on Ebay pretty low priced @$200-$300 with a single port QDR ConnectX2 card. ensure the firmware is @ V2.9 and youll have no problems with Centos.