How to make Chrome open bookmarks and URLs in new tabs?

The default Chrome acts like the default Firefox concerning tabs...

The behaviour of Tabs Mix Plus that you describe is available in ChromePlus. ;-)

(One Caveat about Chromeplus is that they do not update their core Chrome engine version as soon as it puts one out. It is often at least one, sometimes two version numbers behind Chrome)

Hold down the CTRL key when you click on a link/bookmark, this will open it into a new tab.

You can also use this extension.