Since you don't have a lot of time but want to do autograph books. Instead of trying to download pages for each and every character. Why don't you just download a page for each park that you will go to. Penny (Chaoscent), LJCollins and Natalie have generic cards for each park. Then you could make multiple copies of the generic cards and have the characters sign those.
Find the 4 images that you like and if you want to make them easily...save them as a jpeg. Download them onto a disk and take them to Wal-mart (or wherever you get pictures developed) and have them print a bunch of each card in 4x6 size. If you go in the morning they usually can get them done a lot quicker than an hour (at least at my Wal-Mart

Then while you are waiting you can grab some blank t-shirts, look and see if there are any cheap backpacks, get a photo album that you can slide the autograph cards in for each child and you will be well on your way to getting a lot of the things done you were wanting. On the way home stop by a Dollar Tree as they have a TON of disney things that you can add to the backpacks like figurines, activity/coloring books, crayons, pens, little frisbees...all with Disney characters. You could spend $10-20 and fill up the backpacks.
Here are a few links for the generic park cards:
http://s345.photobucket.com/albums/p379/ljcollins_2008/Blank Autograph Pages/
Look at the ones that say "generic"
http://s143.photobucket.com/albums/r132/donatalie/2010 Autograph book/?start=40
http://s226.photobucket.com/albums/dd181/Chaos1Cent/Blank Disney World/
While you are grabbing the blank images. There are some cute covers that you can also get. Paste them into word and put a textbox over the image and add your child's name. Then you will have an autograph cover. Here is a link for how to add their names to the card in MS Word:
http://www.disboards.com/showthread.php?t=2286193 (look for adding a textbox)
If you go again in the future...you can start planning a year in advance and make the individual cards for each character.
Remember that vacations are for enjoying. Whether you make everything possible on the Boards or only take what you have made to date...it will be a great vacation. It is about time spent with family not all the extra things.