ok i am not so sure about the whole routine side of things, i have 5 and 2 of them needed more of a routine and dedicated nap times, the other 3 were cat nappers and slept here and there etc.
but ime SLEEP does BREED SLEEP, so yes the better they nap in the day the better they sleep at night.
but be careful not to end up confining yourself to the house, try and make sure she will sleep in thepushchair etc, my dd is a pita for this, she only naps properly when at home in bed, its great when i am at home, i put her down and have a guaranteed 2hrs! but when we are out and about she WILL NOT NAP, does fall asleep in the pushchair sometimes but only cat naps and i end up with a tired, grumpy toddler who then doesnt sleep well that night.
i have read that those black out covers for pushchairs can be good for encouraging naps when out?
oh and mine have all been co-sleepers as well, so yes it is a pita trying to get them to settle when you have other oens, i found a moby wrap good for this and also LOTS of walking so they woudl sleep in the pushchair, apart from no 5, who wont do that!