Answer:
3.Regarding mouthing:
American Sign Language uses facial expressions, head tilts, shoulder raises, and mouth movements in grammatical ways (non-manual markers). If your mouth is busy mouthing English words it will be unavailable to use for grammar purposes.
It is true that many Deaf do mouth many of the words they sign. The appropriateness of mouthing depends on numerous factors. Some of those factors have to do with whether or not a sign is traditionally done with a specific mouth morpheme (for example: NOT-YET uses a slightly open mouth showing the tongue covering the lower teeth) or whether the sign is a multiple-meaning sign, (for example: single/someone/something/alone/only).
A high level of experience is required to know which signs require non-manual markers (NMMs), which signs have the option of being enhanced by which NMMs, and which signs can be mouthed. Many Hearing, ASL as a second language learners, mouth inappropriately by either overexaggerating their mouth movements.
5.a. Touching
b. Checking with the group
c. A direct communication style
