DFRobot relayboard v2.1

A colleague of me had ordered here 2 relay shields.
I requested for an 8 ports relay board but he got 2 4port relay boards from this site DFrobot

We got 2 different 4 port relay shields to my suprice
We got :
- a Relay shield v1.2
- a relay shield v2.1

They look verry different i was able to find the 1.2 version at this site here with some sample code.
I was unable to find information of the 2.1 version so i have some questions about them

1) Where is sample code for the v2.1 relay shield ?. (link url...)
2) Where is the manual for the v2.1 (it seams to have some control switches what do they do?)
3) Both shields have a power connector;
Is additional power required as our arduino is connected to an usb port ?
4) Are they stack-able, can we put a 1.2 on top of a 2.1 when using an arduino uno?