DSP Development Kit, Stratix III Edition vs. Stratix III FPGA Development Kit

Both kits have the same main board. The only difference is that the DSP development kit includes the HSMC daughterboard with the ADCs and DACs. The Stratix III development kit has the HSMC connectors, but not the daughterboard, and as such can't directly aquire or generate analog signals.

As for the DSP builder, in theory it should support the Stratix III DSP kit, but note that it isn't included with the kit and would need to be bought separately. If you think you need it then you can ask to your distributor before ordering it to confirm that your kit is supported by DSP builder.

Once finalized, you can freeze your design in an Hardcopy III. But again I think that to be sure you should contact your distributor to confirm that a Hardcopy would be compatible with your requirements.