Tension varies, of course, but I wouldn't use 7s with this. 8 would be the minimum I'd try, personally. A center double decrease *might* be possible, but I wouldn't count on it; K2t might be a bit twitchy if you're knitting too tightly, but fine otherwise. And I know that picking up stitches is definitely no problem, as I've been doing it repeatedly. (Yay log cabins!)