Can I Star Cross a unit that Leblanc is trying to copy with her legend ability, and does the reflection token have temporary?

Yes to both. You can Star-Cross a unit LeBlanc is copying, and the Reflection token does have Temporary.

Star-Crossing the copy target: Deceiver's copy instruction is a reflexive trigger that goes on the chain after the Reflection token enters — that's a Closed State window, so you can react with Star-Crossed ([Reaction], 3E). If you bounce the unit she intended to copy, that unit is no longer at the battlefield, so the copy effect fails for it (if another valid unit remains, she can copy that one instead — the target is chosen as the trigger resolves). You can also Star-Cross the Reflection token itself; it's returned to hand and then ceases to exist since tokens can't exist in hand.

Temporary: Yes — Deceiver's own reflexive trigger reads "It becomes a copy of another unit there. Give it [Temporary]." The Temporary is granted directly by the legend ability, not copied from the target, so the token has it no matter what it copies and will die at the end of the turn (Rule 816). This is confirmed by the official Zilean/Deceiver clarification, which notes Deceiver "gives the tokens Temporary."

FAQ #11306; Deceiver card text.