For the clipboard go to Alfred Preferences > Features > Clipboard History, click on the Advanced tab and ensure Auto-paste on return is checked. Then all you have to do to paste an item from clipboard history is to select it and press <return>.
I'm not sure I quite understand the question about snippets as they are intended to be automatically expanding pieces of text when you type the appropriate keyword. Sorry not to understand but what exactly are you wishing to do with them?
