No, the R9 290 does not support DX12.
No, the R9 290 does not support DX12.
It should accommodate it, though full support isn't available yet. Currently, only a handful of cards have complete support.
Support for 970, 980, 980ti and Titan X is fully available on the NVIDIA side. I’m not sure which AMD cards receive complete support, but it seems the R 300 series and all Fury cards are included.