Yas Marina.
Turn 4: I would probably use the inside corner at turn 4. This provides a longer flowing section and thus also more variation to all the 90 degree corners. Might be dangerous with the pit exit just before, not sure.
Turn 5/6: For me this chicane does not add much. This type of corner combo is already at the end of both long straights.
I would propose a less sharp chicane closer to the next hairpin. This has two advantages:
1 A different shape of chicane to the other two.
2 With the chicane closer to the hairpin, the guy in front gets more of a dilemma; either you take the wide line into hairpin in order to maximize exit speed onto the straight, but risk opening a gap on the inside for someone to dive into. Or you cover the inside more, but risk the guy running behind to take it more wide to increase exit speed onto the straight.
See an example below:
Turn 8/9 and 11/12/13: Open up the chicanes a tiny bit more to enable two cars to continue side by side longer and allowing more effective cut backs which with the current layout are useless. Now the overtake at 11/12/13 especially is final because the corner combo does not allow side by side racing. By opening it up a bit more the duel could extend to corner 14.
I think all the above would fulfil the four criteria, because no major restructuring would be necessary.