http://www.cisco.com/en/US/products/sw/cscowork/ps5209/index.htmlThis should give you some good overview of the product

CSD is only suported on Cisco ASA 5500 Series running Version 7.1(1) or later

I believe only hitless upgrade is supported between minor versions but they both needs to running identical software, licenses and same VLAN configurations

Check speed/duplex settings and configure preferred settings manually.Can you post output of show interface ?

Yes it is possible with 3.1 code. You can have upto 8 pairs of interfaces (i.e 8 bridge groups)