Romero, who spent the last eight years in Spain, made his debut in 1995 and participated in two Copa Americas and in the 2002 World Cup.
Schulte joins Carolina from the Cleveland City Stars, who won the USL-2 title last season and have moved up to the USL-1.
New Carolina coach Martin Rennie, who coached Cleveland last year, has also signed Aaron King (Charleston) and Josh Gardner (Seattle Sounders), College players looking to make the RailHawks included Michael Callahan, Garry Lewis and Brian Shriver of 2008 NCAA Division I runner-up North Carolina.
The RailHawks began preseason training on Monday.
PORTLAND SIGNINGS. Another USL-1 that has been active during the offseason is Portland, which has signed six new players, including Guinean striker Mandjou Keita, who earned the Malaysia Super League Golden Boot in 2006 and most recently played for Duli Pengiran Muda Mahkota (DPMM) FC in Brunei, and Swedes Johan Claesson and Antouman Jallow.