From my point of view, zero-cross detection is about getting a pulse with each alternation.
The amount of ILED to allow depends, basically, on how wide you want that pulse to be, as Billysugger mentioned.
Flashover RoT? You could bung this up with resistors till Kingdom Come and still be undone.
Flame-proof resistors. Resistors, Fixed | Vishay
Is somebody submitting the/ir design for UL/CE/TUV/... ?