I have slept with ea of my 5 children until around age 2 1/2 when they
thought they were big enough to sleep somewhere else.  Now all  the oldest
usually wind up sleeping together every night, even after fighting all day.
 Mom and dad have someone to sleep with why shouldn't they?  As far as bad
habits go, make sure the baby is fully awake before offering to feed.  Try
pats on the back ect if just fussing, or even the dreaded pacifier can help.
 I think it also helps to be aware of the research regarding cosleepin and
poss. decreasing SIDS.  It relates to not having to baby stay in deep sleep
so long because of parent movements.