Do you use Stock Footage or Photography?

I've been working on a little pet project related to using stock footage, photography, and audio in After Effects. If you use any stock content from commercial sources like Artbeats, Getty, Corbis, or iStockPhoto, send me a comment to let me know how you use stock content and how it fits into your workflow. Some example questions to think about:

+ what companies do you purchase from?
+ how frequently do you use stock content?
+ which kinds of stock do you use (images, video, audio)?
+ do you use royalty-free footage, rights-managed, or both?
+ once you have the stock footage, do you track its usage?
+ do you charge your clients for using stock footage?
+ do you start working with proxies, then replace with high quality final images?

Thanks!