Deep stream: General Queries

I have following queries regarding deepstream2.

1- How many detectors can be used out of the max supported no of geis(I believe that is 16)?
How deep a secondary Gei can be (like a gei on a gei on a gei)?

2- What is the primary difference between primary and secondary gei(is it like secondary can only be worked on primary geis ?)

3- Will Deepstream3 available as an opensource? Is it possible to get source code of deepstream2?

4- What all upgrades can be expected from DS3?

5- Maximum no of classifier labels that can be supported at once for a secondary gei?

6- How can I integrate yolo as primary gei and then rest which are random uff/caffe models? laying yolo plugin before sgei0/sgei1 in the pipeline? will that cause any trouble with the bounding box/label.

Thanks in advance…