Will players be able to select multiple buildings simultaneously?
We are directing much attention to polishing and improving the user interface. On that note, players will definitely be able to select and build from multiple buildings at the same time. You cannot drag-select buildings, but you can shift-click on them and add them to a control-group for ease of unit production.
Will workers auto-gather resources if the rally point is set to a mineral node or a geyser?
Will we be able to select more than 12 units at the same time?
Currently, unit selection is unlimited, but this may change with further development and testing.
On a given map, will there be one Mothership per map or one Mothership unit per Protoss player allowed?
We are still testing out many possible circumstances in order to make skirmishes more fun and challenging. At this time, each Protoss player will be able to have only one Mothership at a given time, but as mentioned, everything is still subject to change.