A few questions on game mechanics.

What be these questions?

....

yes

Okay.
1. No it doesn't matter NP is always considered as first card.
2. Yes, BQA
3. No it doesn't. NP card placement only affects overcharge which is the NP's added effect.
4. About 150% I think. Doesn't matter don't go around putting something that has a class disadvantage unless if you're a masochist.
5. Yep. Great success 3x on enhancement and Half AP dailies. I had 90 mlillion and by the end of the week it turned to 3 million.

1. NP card position doesn't affect it. That's why most would put it first in a chain.

2. I would assume BQA is best for damage.

3. If all cards are NP, then no, first card bonus doesn't affect NP cards. For more info on the first card bonus check this:
https://grandorder.gamepress.gg/combat-mechanics

4. Class disadvantage doesn't affect the damage multiplier percentage, or rather it isn't directly applied to it. The whole process is multiplicative: the damage multiplier increases your damage, and then then the class disadvantage multiplier halves whatever damage you would have done.

5. Skills require much more QP to level at higher levels. Level 10 requires 20 million QP. The reason most people run out of QP is probably because they save mats/exp for specific servants and then max them all at once, which would take a massive chunk out of their QP. BTW, for QP, millions isn't much at all. Hundreds of millions would be more to write home about. And nah, you don't sound condescending lol

6. Personal note, in future maybe consider writing things out with spaces like this. Makes it a lot easier to read.

just an add-on since most of the questions are already answered clearly.

3. If it's all NP. then the card placement is solely for the OC effect. so make sure you know the OC effects so you can better maximize their effects.

4. It's 200% for advantage and 50% for disadvantage.
Berserkers on the other hand, deal +150% on all classes except the coming (50%)Foreigners and take 200% from everything.
with the exception of our Eggplant Mash ofc.
and Berserkers. They give and take 150% more damage to/from fellow Berserkers.

5. Upgrading skills and Grailing is the first thing that comes to mind that requires a TON of QP. Been there myself. I thought "What's the importance of QP when they don't run out anyway?" Then I found myself an SSR and a couple new SRs and bam. Found myself in QP hell.