hi

i have a simple form where the user can enter in a url of an image, and then this image is displayed on a page. as of yet, there is no validation to check the url supplied. obviously i need to fix this. i have a few questions and id like to hear your points:

firstly, i can do a check to see if the url entered ends in jpg/jpeg/gif/png/bmp but is there a more widespread check available? also i would like to check to see if the image even exists, ie. whether its not been removed etc. is there a way to accomplish all this?

secondly, i am allowing users to enter images from anywhere on the net. the images act as links direct to the website they are taken from. in this case i dont think im stealing copyright, however maybe i need to consider bandwidth problems? if i had 100 images from one site, and each time a user comes to my site this loads 100 of those images, then it could be a considerable load. is there a better way around this? i thought of uploading files, but it seems to be a lot of work for such a small part of my site.

thanks for your thoughts and advice,