Awesome - you basically answered all my questions before I asked them! XD
Just one thing: I thought blocking with your shield was one of the main differences between BB ans DS? Shouldn't I learn to block instead of modifying the game to play more like BB?
Or is blocking not a big mechanic in DS2?
You can play DS2 in countless different ways.
Here's what I'd recommend to you, based on how your previous Souls experience is Bloodborne:
1) When exploring a level, wear armor and use a shield. Cautiously approach each enemy. Be prepared for more enemies to wake up or come out of hiding once the fighting starts. Try to draw enemies away, or use the environment to separate them. Use your shield to block their hits and feel out their moveset, or bait them into attacking and roll back and watch the cooldown on their attacks. This way you can learn when they're vulnerable and punish them.
2) When fighting a boss, it might help to take off your armor and focus on rolling at the enemy when the enemy tries to attack. With the early bosses, this will allow you to dodge most of their attacks. Also note the difference in healing: Your equivalent of a blood vial, the Estus Flask, only has one charge at first, so you'll mainly heal with life gems; when you use a life gem, you start to heal slowly. So when you've been hit by an attack, it's smart to either roll out of the enemy's range, or bait another attack so they cooldown — then you can use a life gem in relative safety.
3) Your ability to dodge is incredibly limited at the start. By leveling up Adaptability, your Agility stat will increase (I think Adaptability is denoted as ADP, and Agility is denoted as AGL — you'll see AGL go up as you increase ADP). Once your Agility is around 100, your dodging should be about on par with Bloodborne (when you're not wearing armor and your equip load is low, I mean — see #4). Until then, you'll have to be much more cautious than you ever were in BB.
4) Equip load is a big difference from Bloodborne. The more armor you wear or weapons you equip, the heavier you are and the slower you'll roll. That's why I recommend taking off all non-essential gear during boss fights. As a BB vet, you'll find it easier, I think.
And like I said, if you find yourself with enough souls to level up seven times (which will often happen after a boss battle), I recommend 2-3 points in Adaptability, and then one point per other stats you want to improve. Note that "Vigor" improves your equip load, allowing you to wear more armor and equip more weapons without slowing down. "Vitality" is your max HP.
OH! And also note your max HP is slightly reduced each time you die, but you restore your max HP when you use an item called the Human Effigy (used as a normal item -- burning it at a bonfire has a different effect).