I just wanted to thank you both for your input. It helped me reach a decision. First of all, I'll start with veteran. As I mentioned earlier I prefer to have my party rest as little as possible and I am not too fond of load games either. Overleveling is always a problem. On hard, even upscaled, chapter 3 was laughably easy after White March. I was actually starting to get bored with fights that were over in a matter of seconds while my party sustained practically no damage at all. White March 2 was fine, but again upscaled chapter 4 was a breeze with even the last boss fight being unable to damage my party.
I never had much of a problem with afflictions, but that was mainly thanks to Durance, who was my favorite companion and the only one who had a permanent position in otherwise varying party composition. I guess I'll alternate between Veteran and PotD if needed, even though I usually don't change difficulty midgame.
I chose Bleak Walker/Black Jacket. I think my main character becomes more of a jack of all trades this way, which may suit a first playthrough best, as I don't know for sure what I'll face. Also I want to dual wield sabers and blunderbusses and I missed the limitations of assassination, nor did I really remember how short a range two meters is in this game, even though it is kind of obvious. Invisibility followed by assassination might have become too repetitive, nor do I really like the glass cannon aspect of that sort of character, especially when hearing that in this game opponents pursue weaker party members even more zealously. Being Black Jacket is more consistent with how my character was in PoE 1 and unlike Assassin makes her closer to the "never back down from a fight" Bleak Walker, who is unafraid to get her hands dirty in a straight up melee. Perhaps I'll create a hireling Assassin instead, as I am still interested to see how the class plays.