From the summary piece:
There is a microSD card slot in the 820. Is it safe to assume it will be hot-swappable?
Tuukka @ Nokia: the battery needs to be removed in order to access the memory card
Will the 820 support 64GB SD Cards? SD XC?
Camilla @ Nokia: Lumia 820 supports up to 64GB microSD cards. SD XC is also supported
How does the microSD appear in the Lumia 820 interface? As an extension of internal storage? Is there any distinction made with where a file is?
Tuukka @ Nokia: the MicroSD is visible in 2 ways: there is a specific set of settings for it: you can set which data is stored in the card and also you are able to see free space on the card. secondly, in the apps, for example Gallery, the data in the device and card are shown to the user - so you can see all your content regardless where it is stored
Why do Nokia Lumia phones not work with standard Nokia multimedia headsets? Is this a Microsoft limitation??
Tuukka @ Nokia: the Lumia 820 and Lumia 920 support also the older Nokia multimedia headsets. we have incorporated an audio jack that is capable of handling both OMTP and AHJ headsets.
Re: speaker volume, guys.... Is it better than the 800/900's?
Tuukka @ Nokia: we have a totally new loudspeaker element on the Lumia 820 and 920 - the improvement is considerable compared to, for example, Lumia 800
Since the Lumia 820 uses an Amoled screen, will we see a comeback of the standby clock/ sleeping screen present in the N9 and Symbian devices?
For the standby clock and sleeping screen, we are definitely looking at the possibilities in that area