1. The egg size is ( 4±3 ) mmx ( 9±2 ) mm. The parents incubate in turn.

2. Based on the MMX 1 sprite design, because I think the boob lights look dumb.

3. Two major reasons are: accessing SSE2 data in memory not aligned to a 16-byte boundary can incur significant penalty, and the throughput of SSE2 instructions in older x86 implementations was half that for MMX instructions.