you can match a intel cpu with a amd or nvidia video card or even a amd cpu with a nvidia card.
crossfire is amd dual video card support and sli is nvidia dual video card support. some motherboards will support both options but is not always the case and the manufacturers website is the best place to check although i doubt you would need to crossfire the 290.
lga 1150 is the cpu socket and z87/z97 motherboards are for overclocking so you can get a cheaper lga 1150 motherboard and there is some pretty cool gaming ones.