1. break 5year continuous residency in US(back to china > 6 months), can she apply natralization 4 years 1 day after coming back to US.
-Yes. If she stayed in China for > 6 months, but < one year, her continuous residency is not disrupted.
2. N400 form, part1, she will select first item of meeting 5 years residency requirment, correct?-Yes.
3. N400 form, part 9, she will list her trip details outside US,
4. If I helped her to filled out form, I will fill/complete part 15, in that case do i need to fill form G-28(I don't plan to accompany her to interview later on).
-No. Because you are not a lawyer, you do not need to file G-28 which is specifically for an attorney.
5. I don't plan to fill part 14, is this ok?-Fine because she knows English (she needa to know English to pass the test for N-400).