1. This is electrophilic addition. Bromine cation attact duble bond enabling attact of bromine anion with simultanous moving of bromine cation to C1. 1,2-dibromobutane is formed.
2. This is radical substitution. Light produce chlorine radicals which can remove hydrogen radical from any carbon. Since radicals at secondary or tertiary at C atoms are more stable so
2-chloropropane predominates as final product.