cal shell modifications

this days im playing around with Geektools
i tried to manipulate some simpler code with success, but “cal” wasnt that simple. In fact, i tried and combined almost nothing, here a snippet of mine:

 cal | sed "s/^/ /;s/$/ /;s/ $(date +%e) / $(date +%e | echo "\033[1;31m"$(date +%e)"\033[0m") /

now, i want to in shell 1 to:
a) strip away Juli 2014
b) colorize current weekday (name) with black
c) highlight the current weekday (number) with red

in shell 2 to:
e) cal from next month

in shell 3 to:
f) cal from previous month

somebody can help please?