New builds are up. They have some bugs but they're usable. I'm busy with other stuff for now.
If you have Facebook installed then messenger won't. I'm not entirely sure why but I don't think it's just limited to signature changes. And for some people even then it doesn't install. At that point you might need to resign the apk
Do you have Facebook installed? Try uninstall in it and installing messenger. To resign, download am app like zipsigner and follow the instructions. Any signature should do
It depends. I'm not as keen on the big apps since