Cannot send/receive MMS on Project Fi with unlocked Blu Advance A6
Well it appears that installing Google Hangouts makes messaging work. Although the app is pretty slow.

For the APN settings, the Project Fi app disables that menu when it's installed according to this: 
https://productforums.google.com/forum/#!topic/nexus/F9TYPTE11to

According to that post, you can run this from an adb shell to re-enable it:

settings put global hide_carrier_network_settings 0