1. Reduce to 30s, no stun OR no range requirement.
2. No. You might as well just say "Grease Lightning has been turned into a passive trait that increases monk damage by 21% and attack speed by 15%." GL3 is not passive for a reason. Monks do amazing damage overall even with GL falling off sometimes, the devs should just balance around that (which it seems they've done).
3. I like Neko_Shiroyasha's idea better. Or replace it with a range attack of low potency.

The only major tweak to the monk I' feel we really need is to increase Twin Snakes buff by 2-4 seconds so we can always comfortably use True Strike.