1) a +4 modifier, even if countered by a -4 modifier, is something extremely rare on a non-Dragonborn modified +0 LA base race. I believe that the DMG has some balancing rules for creating homebrew races, and which penalties are worth 'more' than others. Might help here
I was thinking about changing these atribute modifiers anyway. Maybye switching Dexterity and Strenght to +2 and -2 respectively.
2) Movement speed is usually in 10' increments. I'd choose either 20' or 30', not average the two; 20' seems more appropriate here.