Messages & Chats, Phone & Calls

I've noted that there seem to be 2 installed messaging apps - Android's messages and Chats, which I gather is a Linux app. Similarly there are 2 phone apps - Androids Phone and Calls, which again seems to be Linux. My interest in this came from using SMS-IE to move my chats and call history over. They show up in the Android apps, which is to expected given the transfer app is an Android app. 

However I notice that the Android apps (especially Messages) seem to be more full-featured. e.g. Messages can send messages to recipients while Chats can't. 

This leaves me with 3 questions:

1. why are we using Chats & Calls?
2. is there a way to import the histories into Chats & Calls?
3. are there any plans to add features to Chats & Calls?