Remember that the Replay is intended to be a multi-platform implementation not just Amiga. The expansion ports will allow tailoring of the Replay to support or enhance other platforms for which cores are developed.
Correct. The main board was designed to be low-cost and suitable for a broad range of applications - with just enough on board. What's on there is ok though, 192KHz audio DAC and DVI/Analog/Composite outputs with decent filtering and line driver.
The daughterboard for the Amiga/Atari has Ethernet/USB and an optional 68060 (with associated memory).
Another daughterboard has a JAMMA connector for arcade game cabs.
There is a patch daughterboard as well which as 5V translators on all the IO and a place to wire up other chips (processors / SID etc) for analysis. This way I can run the original chip against the soft copy. I am doing this at the moment for some of the AGA chips to fine-tune the timing.
/MikeJ