Our servers have dual Intel Xeon (Harpertown) 2.0 GHz Quad Core Processors with 8 GB of RAM.

We run CentOS Enterprise Linux. The servers have connection speed on our servers is 100 mbps (mega bits per second)

Is the connection on our shared servers 10mbps burstable to 100mbps or 100mbps constant?

100mbps constant

Is the connection on our shared servers 100mbps up and down or just 100mbps total?

100mbps both up and down