gawk-sed-3

#! /bin/bash

gawk '{gsub(/\n\n+/,"\n\n");printf $0}' RS="^$" file | sed '
s/\s*\([.,;!?]\)\s*/\1 /g
s/\s\+/ /g
s/^.*$/\L&/
s/\([.;!?]\s*\)\(.\)/\1\u\2/g
s/^./\u&/
/\(^$\)\|\([!?;.,]\s*$\)/! s/\s*$/.&/
'
gawk 'END{print "Number of paragraphs: "NR}' RS="" file
gawk -F'[.?;!]' 'END {print "Number of sentences: "NF-1}' RS='^$' file