A primary alkyl halide would prefer to undergo reaction.

reactions occur only if the intermediate carbocation is stable i.e., carbocation.
reactions occur if there is less steric hinderance on the -carbon of alkyl halide. In case of primary alkyl halides, carbocation is highly unstable and steric hinderance is very less. So, primary alkyl halide would prefer to undergo reaction.
In -elimination, proton and the leaving group are present on same atom.
The process of conversion of enantiomer into a racemic mixture is racemization.