I am considering buying the 20xGridseed pack - however, I have a few questions:

1) What size is the barrel plug (2.1mm or 2.5mm) for Gridseed? Also, what size is the barrel plug on the 12V power supply sold on the site?
2) A single Pi can handle up to 32 USB devices (thus, 32 Gridseeds), correct? Will the software support this number? (I switched over to cgminer for more accurate reporting)
3) The mycode10 coupon doesn't really apply a 10% discount as it says in the email, does it? It's more like 5-6% - is this intended?

Regards,
Pandaisftw