Ok, so that's 6.4 cores per mm^2 while Kepler has 4.8. Not bad, considering NVIDIA has already shrunk the scheduling ressources, register blocks and cache sizes per core to a bare minimum (something I don't agree with btw.).
Kepler has 8 "SMX" with 196 parallel sp threads each. For me the number of cores = the number of parallel threads, although on GPU they are not as independent, i.e. each "core" of an SMX either executes the same instruction on adjacent data or does nop. With dual issue do you mean a two stage pipeline or two threads in parallel, both performing FLOP?
"Dual issue" means "can issue two instructions per cycle", independent of pipeline depth or multithreading. In the case of the Epiphany, it can issue an ALU instruction and a floating point instruction each cycle.