1) See point 4. Yep, they will have a big target, but you can screen and give them -2 to hit.
2) Depends on meta. They have a ****ton of shots, and the exarch is really good, however if your meta is exclusively mono-primaris then give them a miss.
3) Personally, I'd go one of 6. Although you lose a wound, it makes them easier to buff and you won't yield killpoints.
4) A cheeky option would be to do an additional alaitoc patrol. Put your warlock as the
HQ, drop the hawks for some rangers, then bring 6 reapers with tempest launcher exarch. It doesn't improve
CP, however your list isn't excessively
CP heavy. This would make your reapers more durable, give you some wounds on small characters and a relatively durable screen.
5) Realistically... I haven't the foggiest. I like them, but I've gotten lucky with rolls. I'd definitely consider conceal if you're willing to make that third detachment. Not too sure about the other powers honestly, I generally avoid
CC on my eldar due to the local meta. I feel like you may want to switch up the powers, it is a bit all in since you only have a single
CC unit, but if it works it works! Again, personal preference on this one.
Reapers are better than fire prims for straight up damage, however they aren't as durable and degrade worse. I'd take reapers, but do give them some protection.
I'd be interested to see how dragons perform! They look strong, but I'm yet to give them a go. Best of luck! List looks good