Android - Quickly input frequent used phrase by choose-and-paste

Personally, I use Quickcopy - It may be as close as you will get to your ideal. The only part it will not do is automatically paste into the field you want it to, but it does provide quick access.

You could try Smart Clipboard: http://www.appbrain.com/app/smart-clipboard/net.xdevelop.cp it claims to do just what you are asking.

Personally I use Uber Keyboard: http://www.appbrain.com/app/uber-keyboard-%28text-voice%29/com.pwnwithyourphone.talktomekbd It give you suggestions while you type which I usually ignore but it also let's you set custom mappings. So I set it up so the 1st two letters of my email are mapped to my full email address so when I type in mw it shows my full email as a suggestion so I can insert it without having to open another app. I've set a bunch of other custom mappins as well for commonly entered things.

I'm the creator of Clipper, a free clipboard manager app. In addition to the clipboard history feature, you can also store snippets, which is what you're looking for.