Clarification of the typo in the Almanac's entry for Intrigue
Ignore ", board)". From a different print,


  With this card you can displace an opponent’s knight without using a knight of your own. You can play this card even if you have no knights of your own. The displaced knight must be moved to an empty space. If he cannot, then remove him from the board (return it to its owner). After the knight is displaced, you can build there or move one of your own knights, following the normal rules.


It's just pointing out that now that the spot will become vacant, so you are able to build there. It's not allowing you play a knight for free.

The normal rules for placing a knight are:


  If you wish to “hire” a knight, you must pay one wool and one ore to the bank. This allows you to take a basic knight (open helmet/one ring) and place it on the board. Newly placed knights are always placed with the inactive up. You may place your knight on any unoccupied intersection connected to your roads.





  why the knight-hiring part wasn't specified in the card?


It's just pointing out a reason for which you might want to use the card. It's barely worth mentioning in the FAQ, much less on an already-full card.


  Lastly, if I don't have a basic knight to place, can I instead hire a knight of higher rank or, say, the same rank of knight my opponent removed?


No. You can only buy a basic knight.


  but only if his/her knight is blocking your road to a common intersection (which is very rare, considering no one wants their road to be interrupted or left open, lest the "Diplomat" strikes).


The knight actually protects its owner's roads in this example. That presents two additional uses for Intrigue:


Remove a Knight to leave a road vulnerable to the Diplomat.
Remove a Knight so you can place your own to protect your road from the Diplomat.