It's done people, it's done! I just finished the last boss (astoundingly on my first attempt with only one vile left - but, I guess that's not too surprising, since I maxed out my axe and I already reached Level 90). So now I can proudly say that I've beaten my first Souls game! :)
Thanks everybody for your sincere help! I have to admit that I just looked up how to get into the choir and how to reach the eyeball monster, since I wanted to finally beat the game and because it is already 3 AM here right now, but that was pretty much the only thing that I blatantly looked up - apart from asking for some specific hints here.
I guess I haven't missed too many optional areas on my first playthrough, although there got to be a few more sidequests that I still need to tackle. So for my second playthrough I will probably just use a 100% guide to make sure to get everything what this game has to offer. Is this easy to get a Platinum Trophy? Or do I have to do some grindy shit like max out every single weapon or something like that?
So some questions to the NG+ : is there a max level? Because I have already reached level 90 - is there a level cap at 99? So far I don't get the feel that enemies are stronger compared to my first playthrough (they need around the same amount of hits as at my first playthrough). Also any suggestions how to keep things fresh on consecutive playthroughs? I've heard a lot about certain Arcane sets that might be fun to use, but since I didn't improve any Arcane stats I might to use a completely new character, right?
Anyway, thanks for keeping up with me. What a truly great game! :)