Ben Harris thanks for your questions - let me answer a few here:
1. You are correct. Once we enable 'encrypt only' it will be considered at feature parity (plus more) to the previous version of Office 365 Message Encryption. You can find details of the encryption standards used here. You should see the 'encrypt only' in the public roadmap very soon.
2. We plan on simplifying the Outlook experience to align with the actions that end users need to take to protect the email. The goal is to make this experience seamless and easy - like the way it is in Outlook web experience. We are actively working on this and will share a date when ready.
3. That's great feedback. Will share back with the team. If you have any other feedback do not hesitate to add them here: https://office365.uservoice.com/forums/289138-office-365-security-compliance
4. Not at this time but it's something that's top of mind for us.