Bookmarks, tabs, and history that are synced are all integrated in the versions of Firefox I'm using (Firefox 9+). To retrieve synced tabs, look for a triangle at the far right of your tab row (near the window controls-minimize/maximize/close), click it and you'll see an option "Tabs From Other Computers". You can also pull it up by typing in about:sync-tabs on the address bar (aka "awesome bar").
Your bookmarks are not divided up by the computer name from where they were created; just open the bookmarks & you'll see them in a monolithic list. History items are treated the same way: Firefox won't tell you where those history items were added; they are just added chronologically to your browser's history.