I am an Elden Ring beginner. I have some questions.

‌I used to only play Zelda on the Switch 2,
but I've been playing Elden Ring as a Tarnished since a month ago.
Since this is my first Soulslike game, I'm struggling quite a bit, barely getting by by watching YouTube tutorials and dying dozens of times.
Even when using Spirit Ashes, it's not easy because the only thing I really know how to do is roll.
Yesterday, I died dozens of times to that Dragon Tree Sentinel in Farum Azula (the one where you can't use Spirit Ashes), and I think I must have died a hundred times to the Dragonlord of Farum Azula because my Spirit Ashes kept dying too.
Anyway, I've finally made it near the end,
but I have a few questions.
1. I need to start New Game Plus (NG+); should I clear the DLC first and then start NG+?
2. Or should I get stronger through NG+ and NG++ first, and then go to the DLC?
3. If I start NG+ without doing the DLC, will the DLC enemies also carry over to NG+ and become stronger?
*Regarding equipment, I was using Moonveil but switched to Rivers of Blood, and I think Rivers of Blood is a bit better.