Need Recommendations For Safety Schools (D22)

A question on how students chances for admissions are impacted in one of the following scenarios . any thoughts?

  1. Students apply to a college/university where their high school has not historically sent any one or not many applied ( do colleges go for familiarity with high school over other considerations while admitting students)?
  2. students apply to colleges where let us say only a small portion of students selected from the school attended? let us say the previous year the college admits 100 students from the school and only 10 or 20 enroll. will that skew the admissions for the current batch of applicants from the same school ( that only small percentage of admitted students are enrolling )

thanks