jamescheong

After you beat the final boss, you can either:
 
walk out of the room
 
kill the maiden in black
 
If you kill the maiden, you get the Old One's soul which is worth 200,000 souls as well as a red eye stone for summoning duels. 
 
Also, all souls from the last boss you kill + final boss + etc can't be used till you beat 1-1 in NG (phalanx). You have to then go talk to the monumental and the maiden will be available to use souls again.

This is, quite possibly, the most anticipated game of ALL TIME

He's not that hard, just stay away from his AOE and jumping attacks, and keep your good grasses on hand to heal up. If you want an easy way to beat him, get him stuck on the ribcage to the left of the staircase -  him on one side, you on the other. He'll keep running towards you although the ribcage is in the way, so you can run around and attack then dash back when he's doing his thing. He'll eventually get around, but you can just run around and get him stuck again.

 http://demonssouls.wikidot.com/bosses

5-2 on NG+
 
I love this game

If you're having difficulty with the Maneaters on NG+, kill the 1st one before you even go in the fog door
 
Shoot a bow from as far to the right of the door as you can, it'll go through the fog door there.

I doubt a DLC - there's a concept art piece that shows like a million people streaming into the northern lands, with a bunch of the giants fighting them. The whole place was probably destroyed story-wise.

Only reason to keep repeating the game on NG+, NG++ etc is for pvp in my opinion. At that point in the game, you're going to be facing off against people fully decked out with gear, stats and spells tailored to their play style. The game is considerably easier once you beat NG+ because the difficulty only spikes from the original to NG+. After that, it's only a very small increase in difficulty each consecutive playthrough. Also, you'll be continuing to add to your own character - you might have started off pure melee, but you can start putting points into magic/miracles if you'd like so you can be a hybrid - no need to start over and make someone that is a magic user or hybrid from the start.

Easiest way is to use the ribcage left of the staircase. Get him on one side, you on the other - he'll keep running towards you even though the rib cage is in the way. When he's stuck like that, go and take a swipe, then run back - eventually he'll get around, but then all you have to do is run to the other side and start over. Watch for the AOE attacks, but they're not hard to evade.