I think devs does not matter their cryptocurrency, they already have self exchange. Just used ICO as a financing option.
Which self-exchange? They are only listed on Etherdelta, DDex at the moment and don't have a good exchange.
As per their recent medium article they are paying SXDT holders a dividend. Is it for ICO investors only or for all holders?
It is for all SXDT holders. But you must hold tokens on metamask, Ledger nano or Trezor wallet. Although I have a problem with withdrawal from my Trezor. I'm not sure how much it is worth keeping this tokens.