I found the game to be a little easier than Dark Souls 1 - after they released the patch that allowed you to turn human after helping someone beat a boss. Before that it was tough managing human effigies but after that I would just help someone with a boss, get the tricks down pat, and then take it on myself.
I thoroughly enjoyed Dark Souls 2 and it was the perfect difficulty for me.
It doesn't happen often in the gaming industry but when it does I'm impressed - they completely revitalized a game and made it better than it initially was. Final Fantasy XIV did it and not Diablo 3 did it. It's the game it should have been and the teams need to be commended.
I would go with Knight. He starts out with one sword and no shield and you can get the feel of dual wielding early on. If you like it - you can go down that path.
Starter class doesn't really matter all that much in the grand scheme of things. You can build your character however you want, the starting class just decides how you begin your DS life.
If you are new to the series (or not a pro like you said) the shield is going to be key. Playing a high dex build (moving around a lot, dual wielding, etc.) can be very tough. I would save that for a second playthrough if that's your thing. Learn with a shield.