Barnsley have signed striker Johnson on loan for the rest of the season. The 21-year-old has not featured in the first team this season, having already spent time on loan with Championship rivals Sunderland and League One side Doncaster Rovers.
Johnson will now see out the current campaign with Paul Hart's side.
Another striker, Reeves, has joined Conference club Scarborough on trial, after also failing to make a breakthrough into the Elland Road first team.
Meanwhile, Drogheda United have handed trials to youngsters Tyrrell and Cousins.
19-year-old defender Tyrrell and 20-year-old midfielder Cousins are looking to impress and earn a deal with the Eircom League Premier Division side.
One player that has arrived at Leeds for a trial is Newcastle United reserve goalkeeper Adam Bartlett, after Liverpool's Paul Harrison ended his loan spell.