Sorry it took a bit for me to get back here...not on SDN as much anymore for whatever reason.
Ill try to answer you from general to specific:
Your main hate, iTunes, has come a long way. Even if you didn't just use iCloud to wirelessly sync and upload any new content (which is the best way), you can drag and drop like you prefer. Drag and drop works with any media...music, pics, movies...etc.
As for books...you can use iBooks, Nook or Kindle app. So, the iPad has the same functionality of nook or kindle, but then also adds iBooks. Sometimes people think iBooks is the only app, but its just Apples app. That being said, iBooks has accept ePub (as a format) for a while now, so youre good to go there as well.
For movie formats, you need mp4 for the native app, but there are several apps that play any type of movie file. They work just like DivX or VLC does on a computer. For me, to keep it all homogeneous, i just use handbrake (a free computer app) and convert all my movies to mp4 anyway. But, iPad can run the other stuff if you really dont want to convert.
So, you can see that iPad does pretty much everything...and as for connectors, the adaptor is the only way to physically connect. But thats so old school anyways 😉 theres usually a computer already connected so just email the item to yourself and play it from anywhere.
Hope that helps and let me know if I missed something