At the command line:

FOR %i IN (*.png) DO convert "%i" -quality 100 "%~ni.jpg"
FOR %i IN (*FA.png) DO convert "%i" -size 2560x1024 -quality 85 "%~ni.2560x1024.Q85.Clean.jpg"
FOR %i IN (*85.png) DO convert "%i" -size 2048x1536 -quality 85 "%~ni.2048x1536.Q85.Clean.jpg"
FOR %i IN (*FA.png) DO convert "%i" -size 640x256 -quality 85 "%~ni.640x256.Q85.Clean.jpg"
FOR %i IN (*85.png) DO convert "%i" -size 512x384 -quality 85 "%~ni.512x384.Q85.Clean.jpg"

In a batch file:

FOR %%i IN (*.png) DO convert "%%i" -quality 100 "%%~ni.jpg"
FOR %%i IN (*FA.png) DO convert "%%i" -size 2560x1024 -quality 85 "%%~ni.2560x1024.Q85.Clean.jpg"
FOR %%i IN (*85.png) DO convert "%%i" -size 2048x1536 -quality 85 "%%~ni.2048x1536.Q85.Clean.jpg"
FOR %%i IN (*FA.png) DO convert "%%i" -size 640x256 -quality 85 "%%~ni.640x256.Q85.Clean.jpg"
FOR %%i IN (*85.png) DO convert "%%i" -size 512x384 -quality 85 "%%~ni.512x384.Q85.Clean.jpg"