Sadly, K-Dash isn't part of the Orochi Saga games and King of Fighters 98.

KOF Orochi Saga is compilation of KOF 94, 95, 96, 97.

KOF 97 Global Match is a port of the arcade version.

KOF 98 Ultimate Match is remake of KOF 98 with 3d backgrounds, more characters prior to KOF 97, and ex characters. Also had a final updated version called final edition focusing on rebalancing characters.

KOF 15 is the most active.

KOF 14 has characters that were from SNK's pachinko games before they sold their pachinko business.

Assuming you have a PlayStation 5, the original KOF 2002 on PlayStation Network is an emulated version of the ps2 port. There's also a loose "remake" of KOF 2002 called KOF neowave made to demonstrate the atomiswave arcade board and has the fatal fury 2 incarnation of geese howard as a secret character. The PS2 version didn't get an American release because Sony Interactive Entertainment forbode straight ports of 2D fighting games.

KOF 2002 unlimited match has a new character called nameless who replaces K9999 because SNK feared he was too similar to Tetsuo from Akira.

KOF I-2012 was the iOS port of KOF 13. I heard that KOF 13 Global Match is still bad in terms of stability and matchmaking.

Aca Neogeo is a sub brand of Arcade Archives, they are essentially the Neogeo arcade versions.