Re: yes, Master?
I got my kits from Zoombicycles and they all came with 2 master links.
As for the chain tensioner ~ I would recommend getting rid of it. They pose a serious danger in that they move all too easily and can get caught in the spokes or drop the chain ~ either of which can ruin an otherwise very enjoyable ride...
All I had to do was remove an extra 2 links from my chains and the rear wheels/pedal chains had the right amount of slack to move the wheel back and make both chains tight. I also had to cut my fenders a little further, but it seems that everything about the increased security & smoothness of the ride makes it soo worth it. I've heard about chains stretching, but I'll adjust for that and overcome that issue if/when it ever happens.