Just so Kuro doesn't go crazy, I'll attempt to try and answer these for you, Vagabond.

1. Yes, assuming you have unlocked both the Dark Knight and Paladin specializations, you will be able to unlock both to their full potential.

2. Sword/Shield and Great Sword are being used as examples here. That's not to say that a DRK won't be able to equip a scythe as a specialization only weapon type.

3. Yes and no to this one. Yes, you only get a certain number of points to spend, but you can reallocate them however you like. There's no need to make a new character to explore all the options, but you can't have all the skills active at the same time.

Jericho and I just discussed an option that may address some of your concerns about limiting cross class choices, have a look at the last few pages for more info.

Edit: Oh, looks like you did have a look. Rockin'.