Robin Hood? I didn't know he wrote any books
As for Liveships trilogy and it's relationship with Tawny trilogy...
******************SLIGHT SPOILER ALERT***************************
Well, I for one would recommend you read them as you do learn more about the Fool in Liveships, he/she is one of the main characters! They are also wonderful books and I love them dearly.
Also, you will learn why the ships are live... all is not what it seems young warrior!
So if it's my advice you're after then yes, read Liveships before Tawny as the story slots together nicely and well, that's reason enough really!!!
xx