You can adjust their height and width after you load them in. To know when they are loaded in, you will need to use the MovieClipLoader class.
can i use loader class for multiple image? using loop ?can u please give me example using xml
You can use the MovieClipLoader class to load multiple images sequentially (one at a time), but you wouldn't use a 'for' type of loop...instead you would use a recursive loop, where a loading function is called after each load completion until all loading in done. This is done by utilizing a load-complete listener to trigger loading of the next image. So you start the loading process by loading one file, when that file is determined to be loaded, the listener proceses that file in whatever way you need to prepared (resizing, etc) and triggers the loading of the next file.
If you look up the MovieClipLoader.addListener method in the Flash help documents there is an example there that uses the onLoadInit event. You would be wanting to use the onLoadComplete event.