ipad info

my daughter got an ipad as a gift and currently my wife has an ipod with an itunes account and I have my own. Since my kids use my wifes ipod touch quite a bit I synced the ipad to her computer and loaded her songs. What happens now if I connect it to mine, will it delete all hers and take mine or will it add my songs to it as well? Also if we both have movies downloaded or ibooks can we get them all on the ipad or just one persons. Last question, is there any way to download a movie and get it to the ipad besides buying from itunes?