Great feedback - Thanks!
The order people are listed in is the order you started following them (most recent first). For cases where we know we have the whole list, we should look at providing sort options.
Tapping on the avatar in your timeline should open a 'mini profile' view that shows the slice the person belongs to (if any) and allows you to add them to a slice.
Agree, we need an easy way to mark all DMs as read. We be coming.
The birdfeeder number should be showing you the number of items in your timeline you have not seen (not scrolled above)
There should be an add to slice button next to the unfollow button in the Profile (Biography tab). If you are not following them, tapping follow will then add the add to slice button.
Jumping in timeline and slices is an issue that should be fixed in v1.4. We will keep looking at this.
Unread items by slice is something we are looking at.