Nice job, OP. I think you're on the right track based on the rumors we've heard thus far.
I agree with some of the other posters that have said that Settings will have more utility (expose Bluetooth and Wifi toggles at the top level like Airplane mode, etc).
For messages, you're missing some of the common elements that exist today I think are helpful:
- Date and time indicators for the beginning of exchanges
- Delivered/Read indicators on latest message sent
- Timestamp on latest message sent
I also wonder if they are interested in adding avatars like Messages on Mac or if they feel it is unnecessary or consumes too much space? Maybe they could add the avatar to the left of the person's name you're texting? These kinds of visual queues are helpful so that you don't message the wrong person, etc.