If you have downloaded preset packs to an Android device you can easily transfer them to an iDevice using an FTP client or iFunbox. iFunbox is a free application for PC and Mac that transfers files and folders to iDevice apps. Some apps don't allow folders, but Caustic does. http://www.i-funbox.com/
You can also transfer songs in progress this way by going to the Song folder and tranferring the file with the name you gave it and the .caustic extension. This is great for me as I take my Android phone to work but leave the iPad at home. I can work on a song on my lunch break and then tweak it even more that evening or weekend on the iPad. I will probably lose these extra Christmas pounds by skipping lunch and making music instead. The Caustic diet plan?