Hey everyone just newly registered here after a few months of lurking . I'm just wondering how you all deal with allowing users to upload photos to your site. My main questions being:

How do you stop users uploading incorrect files eg. exe's instead of jpg's etc?
Do you allow them upload it straight to a Db or just the link to it in the Db?
Do you have a function to rename the images so they can be displayed on your site?

Hopefully not a stupid question

Thanks.