Regarding the first question, N70 with latest firmware (5.0638.3.0.1) support AD-41 Adapter.

Changelog for N70 firmware V 5.0638.3.0.1

New features

* Support for the AD-41 has been added in 5.0638.3.0.1. AD-41 provides
remote control for Music Player and Radio functions. Note: the
functionality of AD-41 with N70 is not identical to that of other
products as the Music Player is different. (e.g. N73).
* In the Music Player main menu, the stop, next/ffwd, back/rwd keys
have no response when a track is playing.
* In the Music Player sub menus, the play, stop, next/ffwd, back/rwd
and volume keys have no response while a track is playing.
* In the Active Standby UI (i.e. when music is playing in the
background), the volume control graphic is not updated when track
volume changes are made using the AD-41 volume keys.
* AD-41 also has an integrated mic and provides call handling controls;
accept incoming call, end call, voice dialling using SIND feature and
in call volume control.
* New themes have been introduced with a new default theme for the
Music Edition.
* In the Music Edition, the Music Access Key replaces the Multimedia
Key (sometime called the operator key). This is not user configurable
and locked to always give instant access to the Music Player
application with a short press. A long press gives instant access to
the Visual Radio application.

Improvements

* Week 19 of the Access Point Configurator (APC) is included in this
build
* Bluetooth connectivity: N616 carkit IOP improvements.
- radio & musicplayer use theme background
- gallery is faster
- Yahoo search included
- operator Oscar CZ now named Vodafone CZ
- restart via 3rd party apps no longer possible
- Flashlight app isn't working anymore