Twitter allows users to upload one image per Tweet. Additionally we'll only display one image from third-party apps, though you're welcome to include as many links to third-party app photos in a Tweet as you like.
You can delete an image by deleting the Tweet containing this image. Once a Tweet is deleted, the image will be be unavailable. It may still be cached in some browsers and servers, but the image will no longer be available from Twitter.
Yes. You'll be able to view images hosted by most third-party image providers indefinitely. All photos uploaded from Twitter for iPhone, Twitter for Android, Twitter for iPad and twitter.com will be hosted by pic.twitter.com.
Protected Tweets will work the same way with images as they do with text-only Tweets; you won't be able to see images from accounts with protected Tweets unless you're following the account.
We remove the Exif data on upload. It is not available to any consumers of your image.
Yes, you can do this by replying to the Tweet containing the image.
Yes. You can view individual users' galleries on their profile pages. Read more about it here.
Unless your Tweets are protected, there is always a chance that your image will appear in search results. If you have a protected Tweets, your images should never show up in search results. Deleted images will not show up in search results.
There is an image upload API but it is not available to third-party developers yet. Third-party developers will be able to access the image API shortly after we've rolled out the feature to all users.