It's not very hard to raise ducks. Despite what books and websites would lead you to believe, ducks are actually very easy and fun to care for. Every day you feed them and water them and about every week or so, clean their coop. They are slightly more difficult as chicks as they make big messes but that can be fixed with a large brooder and 2 or so cleanings a day. As for living with chickens and geese, I'd say they might be able to live together, but for the most part it's usually a good idea to house waterfowl (ducks & geese) separately from land fowl )chickens & turkeys & guinea fowl etc). I was only just 12 when I got my ducks and I've only lost 2 out of the 13 I started with. One was from a natural death, he was a runt, and the other got decapitated by a rat. Even now, in Winter we're doing fine. Ducks don't need a ton of care and in return will give you eggs, chicks, love, and entertainment. My dog gets along with my ducks and practically tried to raise them and ducks will keep you laughing with their hilarious antics.
Good Luck!
P.S. Just a word of advice, don't go nuts researching, for all the research I did, when it came down to it I just trusted my gut and did what I thought was right. Don't get worked up about little things either, ducks are very resilient and heal quickly.Just remember, if you love and care for your ducks, you'll always do the right thing for them.