How did Remus get brown eyes, feminine features, and enormously bushy brown hair? I can certainly see the black-haired man as Sirius, but that huge head of curly hair just screams "Hermione".
I agree with you, however, that Remus and Sirius make a good pair, as long as Remus is willing to disregard the "prank" that could have ended with Remus executed for murdering Severus. I suppose Remus is just a natural beta-wolf, and will go along with anything his alpha does no matter how much it could harm him personally. Ah, true love!
From the way Remus told the story regarding the Prank in PoA, I'm guessing he did forgive Sirius for it. Lupin pretty much struck me as the sort of person who'd do anything for his friends, because he doesn't have much to begin with. He'd forgive Sirius anything.
Likewise, there's also the scene where Sirius says, 'Forgive me, Remus' and Remus says, 'And will you forgive me for thinking you were the spy?'. They do. 13 years of suspicions and deaths and hurt, and they forgive each other so easily. I'm not saying that's true love or anything. Just deep friendship.
As for the way Remus looks, JKR never said what colour his eyes were, just his hair. And the illustrations for the American edition does have him with long wavy hair. *shrug*
So amber eyes are fanon, not canon? Slip-up on my part!
I think you're right about Remus's desperate need for friendship. There has to be something unusual going on for him to completely disregard the actions of a "friend" who tries to make a murderer of him. Sirius apologizes for suspecting Remus of being a spy, but he never shows an iota of remorse for trying to have Remus kill Severus.
I find the power dynamics of the Marauders to be the most interesting thing about them by far. It isn't always pretty, but it's always fascinating. Love 'em!