you should be able to but I think you have to download them again just like I had to when getting iBooks on the iPhone and wanting to have my books on the iPad go to the iPhone. All you have to do really is go to the store>purchases>and download them... Right now you have to download them one by one.
Also if you sync the iPad with a book on it it will sync the books to the pc and appear on a new two( you will have music ringtones books apps and so on) if the ipads are linked to the same account you can just sync that way.
Yes. it is possible to transfer the iBooks to your computer.
There are many softwares available in the market that helps you to transfer the ibooks and create backup file of all the files on your iPad. You can easily sync your eBook, video, music, pdf, epub etc from iPad directly and safely and also recover them easily and swiftly again on your iPad. However you can also use the iTunes provided on your computer to create the backup file for iPad data. But because of some problems like synchronization and not being able to support the video files and images the iTunes sometimes are not preferred by the user. Instead of that they use backup software to create the iPad iBook backup so that their images and videos can also be saved and recovered safely.
You can easily transfer iBooks from your iPad to computer or vice-versa with the help of effective third-party iPad File Transfer. After transferring data to computer you can do iPad to iPad transfer in an easy way.
If you want to transfer iBooks from one iPad to another iPad, you can take help of inbulit application known as iTunes. But the moment, you go to the sync option of iTunes, it will start transferring your data and overwrite the files that are stored at the default location. So, to prevent your file stored at the default location, you need to copy your files of default location to any other safe location and then start transferring your file. But in case, if you are not able to transfer eBooks from one file to another, then you can take help of iPad File Transfer Software or for more information, you can visit : http://www.ipadfiletransfer.co.uk