A Flickr photo widget for your blog. Specify the photo tag id and the API Key, it randomly displays one photo from Flickr with that tag. Eye candy!
No. It grabs a list of photos from Flickr, based on search terms you provide, and then selects one of those photos on the rendered page. It does not cycle through photos.
If you refresh the page, it will randomly select a photo again. It will probably be a different photo, but not always.
To get an API Key, you need to visit http://www.flickr.com/services/apps/create/apply/
Walk through the steps. Copy and paste the API Key to the appropriate place in the Widget configuration menu. You don't need the secret.
You need an API key from Yahoo so that the requests that your wordpress page sends to Yahoo, will be tracked and allowed. Every time the page loads, it sends out a request to Yahoo, and gets a list of photos. Yahoo wants to know who's asking for this information, and the API key lets them track that.
No. The API key is free to get; I don't speak for Yahoo, but it seems to me they use the key only for tracking purposes.
Yahoo may throttle the level of requests if you use this plugin on a heavily loaded site. In that case you may need to use OAuth2.0, which I have not yet built into the plugin. But I could be convinced, for the right price. ;)
No, I haven't built that capability into this simple plugin, just yet. Let me know if you have strong requirements in this area.
Yes, the plugin will cache results for each search term. The responses from Flickr can be 15-20k. The response won't change from one page view to the next, so caching makes sense.
The search response cache is keyed on the search term. If your picture term is "pizza|beer", there will be two distinct cache files maintained.
You can configure the lifetime of items in the cache, via the configuration panels in the wordpress backend.