Would like to have an ItemSend event in the web API just like the regular API does. Is that on the planning stage for future releases?

The Universal App Mail (Outlook mobile) is definitely used a lot and is a solid candidate for being the mobile friendly Outlook client people were looking for.
Unfortunately, the version 17.6525.42271.0 does not support office add-ins. I did not see a roadmap indicating it will be, but that would be a huge plus. Now the only mobile approach to consume add-ins is with a fallback with Outlook Web Access.

Current the mail apps can only be activated in read/compose. It would be helpful to allow mail apps to be available at Outlook application level such as in a task pane docked to main outlook window.

The scenario is as follows:
I have a backend document management service to be exposed in Outlook main window all the time. So I can drag/drop email to our document store.

Currently the custom properties stored within an item are scoped to the user's mailbox. It would be great if we could access them everywhere. For example a scenario:
Compose form which will store facilities required for a meeting within an appointment. In webmail the receptionist could open the read form of the appointment and see all the required facilities stored in custom properties.

Currently this is not possible, because the receptionist is viewing it from another mailbox where the custom properties are not available.

In the past I've enhanced the users experience in contacts using a custom form/form region and would like to expand that to the contacts in Office 365.

Extend the mailitem.to.addAsync() method to accept the custom email formats i.e 'Kiran123@/CO=OT' or.'RFAX:KIRAN@/FN=111/VN=1111' etc.
Currently "Office.cast.item.toMessageCompose(item).to.addAsyc()" method is not accepting any custom email address. It is throwing the following error message.

"No valid recipients were provided"