I got these short OTG cables a while ago and just odered another pair. The price is great and they work well. I don't have a BT keyboard, but I tried my wireless mouse - plug in the dongle and you have mouse! But I haven't really seen a need for a mouse with a 7" SGT2.
I use it mostly for attaching flash drives. It DOES NOT work with portable hard drives.
http://www.ebay.com/itm/300701358749#ht_891wt_1037
Edit: The short male OTG cord works to connect to the computer. I use a retractable USB extension cord that's always attached to my computer and I just attach the cord and Tab to that. Only thing is it doesn't show up in the "Safely remove hardware" on the computer.
Short cord also charges it.