Is there any indication anywhere that synching is actually happening? 

If I delete a bookmark from my desktop will this deletion also take place on the laptop, and vice versa, it seems not? Yes, it just has to sync the changes to the other computer. Grab some coffee or a break after manually syncing by Tools > Sync Now ' If I go into 'Manage Account' on my Desktop I am also offered 'Sign out', why is this? Just in case you want to sign out of the account. If I get a new computer, install Firefox and enable synch will my bookmarks be available? If you sign into the account also attached to the other devices, then yes. Is there any indication anywhere that synching is actually happening? There are timestamps in the about:config page, active tabs in about:sync-tabs and new bookmarks and passwords show up when the sync has completed.