I think having heroes react then make attempts to act before villains/challenges react then attempt to act works. The react and attempt can be compressed into one post that way. Having players decide their own order seems fine. I'm not sure how villain orders are decided though.
Thank you for the tips on Stunts. A man charging through a hail of gunfire unharmed due to his superpowers would be pretty scary.
As for Loki, I could direct Loki for one turn. I would like to have him try to create an asset. The asset being an illusory spiderman which can be leveraged by other heroes to distract villains.
I think I will have Hercules is going to try to save some hostages. Maybe pull off the bank safe door have some hostages sit on it, kick the collapsed door, and have the hostages sled away to safety.
Posting soon.