iBooks Book Storage & Sync

Hello,

I have recently purchased and downloaded an ePub book from a website, and safely kept it on my ~/Books folder. To read it, I used Add to Library from iBooks for Mac. I noticed that it then copied the whole book (630MB) to ~/Library/Containers/com.apple.BKAgentService/Data/Documents/iBooks/Books

1. Is there a way I can prevent it from doing so?
2. If my Mac is destroyed now, and I sign in with my same iCloud account onto another new Mac, and download iBooks... will I find this book? In other words, is it synced to the cloud as soon as it's added to iBooks, even it it has NOT been purchased from Apple's iBook Store?

Thank you!