You have to be a translator and contribute to translate parts of Twitter into other languages.
The Twitter icon is a little blue bird. Presumably they used a bird as they 'tweet'
Tjetz is a famous twitter icon .
Twitter allows for a small square icon to be uploaded and that's all that's built-in. Google will yield a number of sites designed for uploading pictures to twitter and most of them integrate pretty well. try http://twitpic.com/
Your header is the picture behind your icon and bio. (Your icon is like your profile picture)
Save a gif to your computer and upload it as your profile picture on Twitter.
You can't copy and paste images on Twitter.
73 x 73
If you have a custom icon you can simply upload it where you would normally upload your display picture.
Twitter doesn't store a "history". You can delete a tweet by hovering over it and clicking on the trash can icon.
Its means that person is a translator i think.
To get the follow me icon get the like button code through your Twitter account. Then copy paste this code into your tumblr blog. Go to Tumblr Dashboard >> Your Blog >> Customize >> Edit HTML Here paste the Twitter like button and place it properly.
Go to your settings, click on "profile" and then "delete this image".