Yes, and yes, and yes, and yes. For real though. Haha.
1. More airflow, better flavor (IMO), can certainly be taken to higher wattages, and it doesn't whistle like a freight train (hits like one though), only downside is there is no RBA for the Arctic (not like you really need one).
2. I own both.
3. In my opinion, yes. The only upside to the delta 2 is the RBA section, but you have to buy that separately anyways.
4. If you use the .5ohm coils, most certainly! And you can even use the .2, but they are pretty weak (for my taste) at 50w.