Are there any other canon BtvS/AtS pairings or friendships that remind you of Xander/Buffy on some level?
Xander idolizes Buffy. She's his hero, and he respects and believes in her completely.
A similar relationship is S7 Spike and Buffy (lol, you know I can always relate everything to Spuffy!).
Spike believes in Buffy, he supports and lifts her up. Also, Spike is not scared to call Buffy out on a bad decision. This is how Xander is with Buffy, too. When Buffy's about to or has made a mistake, Xander is not afraid to call her out on it and set the record straight.
Also, Cordy and Angel pre-romance. They had a real friendship not based on any sort of agenda based on mutual respect and admiration.
And last but not least; Willow and Xander; true friends 'till the end, no matter how much each screws up. 🙂
How do you interpret Anya's "When things get rough, he just hides behind his Buffy / Now look, he's getting huffy, 'cause he knows that I know"?
I intrepret that line as Xander's insecurity of Buffy always having to save him manifesting its self in his subconcious.
Xander, naturally, wants Anya to think of him as a self-sufficient man, not completely dependant on Buffy. We know that Xander has in the past felt inadequate because Buffy always has to save him (he tells Willow this in "The Replacment"). So, of course Xander doesn't want Anya - the girl he's trying to impress - know that he needs a girl to save him. Also, I think that what Xander meant was that he gets emotional support from Buffy, too. He talks to her about his problems and confides in her. His relationship with Buffy is probobly something he wanted to keep seperate from Anya for whatever reason.
Do you prefer Xander/Buffy as a platonic or a romantic relationship?
I prefer them platonic. I honestly think that Xander and Buffy's friendship is one of the most beautiful and authentic pairings in the show. If they went out and ruined that somehow, something would be lost in the series, in my opinion. I do not think it's worth risking such a great friendship unless the two people are really in love - and it's clear Xander is NOT in love with Buffy. I honestly don't believe she sees him romantically, either. I think, for a while, she wanted too, because it "made sense." But, in the end, she doesn't love him like that.
Xander is Buffy's truest friend, and Buffy is Xander's hero. He's always stuck by her side. He's loyal and caring. I'm terrified of the gulf that might be created between them as a result of Angel. If it takes Buffy having to choose, I hope to God she chooses Xander.
(btw, nice questions!)