Two of three characters through the challenge and I got every new exotic adept weapon and every legendary except the rocket launcher. Hoping to get the Hunger with my last character run. It has been very generous.

Ofc, weapon and armour rewards are every character but emblems are once an account permanent. featured completion rewards are per account every week

The first time you do the raid you get an ornament. Only on your first character tho its 1 per account. Then each time you complete a challenge you get 1. So if you do all challenges on 3 characters you will have 7 ornaments. The weapons will drop at each challenge on all your characters tho. So you can get 6 primaries if you do all of it.

Yes, I ran it last night with Titan and then Warlock. I can confirm you can do the challenges with multiple characters. If you do both challenges, you'll receive a total of 3 Armor Mods per character. I received three on my Titan and 3 on my Warlock. I'm not 100% if it's guaranteed or if I just got lucky, will have to wait until next week to tell. On my Titan, I received the Word of Crota (Adept) and Song of Ir Yut from Death Singer challenge and then received Fang of Ir Yut (Adept) from Crota challenge.