I bought an iPad for similar reasons and yes, the retina screen is great to look at. I have an app (Foliobook) for showing finished photo's. But doing the same on the go with RAW's has been a struggle.
If you want to delete on the ipad, you have select them one by one.
The official way is probably through iTunes with the ipad connected to the PC. Let's just say itunes is not my favourite programme.
If you remove with explorer, you can only delete the files in the DCIM folder, not the previews (and they are big) the ipad generates and stores in another place [or 2?].
All in all, I don't regret buying an ipad, but using it I've discovered I want more in photography with a tablet. So next time round, I'll probably look at something else, that integrates better with my desktop.