Short answers, pulled from the story.
Final Fantasy IV for Nintendo DS was released in North America on the 22nd of July 2008. It had launched in Japan on the 20th of December 2007, as part of the Final Fantasy series 20th anniversary celebrations, and reached Europe on the 5th of September 2008.
The Augment System in the Final Fantasy IV DS remake allows players to transfer character-specific abilities to other characters, including temporary party members. Up to three abilities can be given to a temporary character, who will yield abilities in return when they leave the party. It replaced the system from Final Fantasy IV Advance where temporary characters became permanently playable.
Matrix Software developed the Final Fantasy IV DS remake, the same studio responsible for the Final Fantasy III Nintendo DS remake. Takashi Tokita served as executive producer and director, Tomoya Asano as producer, Hiroyuki Ito as battle designer, and Yoshinori Kanada wrote the new cutscenes.
As of July 2008, the Final Fantasy IV DS remake had sold 612,044 copies in Japan and reached 1.1 million copies worldwide. It received a Metacritic score of 85/100 for the DS version based on 52 reviews.
The Final Fantasy IV 2007 remake is available on Nintendo DS, iOS (from 2012), Android (from 2013), and Windows via Steam (2014 in the west, 2020 in Japan). It was later released on GOG.com on the 29th of January 2026.
Megumi Ida was selected from approximately 800 applicants to perform a new vocal arrangement of "Theme of Love" for the Final Fantasy IV DS remake. The arrangement was by Kenichiro Fukui with lyrics by Takashi Tokita, and the song appeared only in the Japanese release over the ending credits.