Re: power managment??
As for the pull-up or pull-down resistors, I don't know what you mean by internal or external... Most of the time this is determined by the ICs you need to use. If there are internal resistors where you need it, then no need to add external ones. If not, then you must use external resistors.
There's no best choice between pull-up or pull-down, it all depends on what the resistor is used for. When it happens that you can use either one, then choose the type that will be inactive most of the time. Use large resistor values, but be carefull to chose a value that bias the input where it is tied properly.
Best of luck,
cyberblak