1) My sister is teaching her 4 year old daughter with "Teach Your Child to Read in 100 Easy Lessons" What should be the next step for her?
For most students, the next step is Reading Mastery III which you can find on EBay. Another option is Horizons 3/4 (the other Direct Instruction curriculum) which squeezes two years on instruction into one year. This is also available on EBay but more difficult to find.
2) What does Singapore Math (the new CA standards version) look like from the perspective of Direct Instruction?
I'd say that SM is a good coherent curriculum that requires a fair amount of teacher skill to teach. Lacking such skill, a good alternative is to use the DI math curriculum Connecting Math Concepts as the primary curriculum and supplement it with SM (and Saxon for the die-hard).