As Asm noted, there are many advantages of having friends at Top 11. Gifts, possible support at games, buying players, friendly games with somebody else than the unbeatable Mourinho...
I send friend requests to people who buy my players so I can watch them shine in a new team, also to people who lost to me in auctions.

As for the poor performance players - I recently bought a player who gets only '6' ratings, but I'm fine with that as long as he keeps doing his job, and he surely does that. Poor performance is not likely to improve, but I would wait and see if you can change that. I've noticed that a change in the player stats may affect the player's performance so if they're fast trainers, maybe shift their skill point a little bit?

In my team my players always have the maximum bonus so I don't know the difference, but my more experienced friends claim that it doesn't affect motivation... I tend to believe that it's better to play it safe - if it might help, then why not?