I assume this is QuickSync? I-Frames, P-Frames and B-Frames are a component of H.264 and the explanation is a long one. Wikipedia has some good diagrams and stuff.
QP just means how much quality to give it. You can set the quality of I-Frames and P-Frames differently. There honestly isn't a whole lot of reason to do this, it's quite specialised and not for general streaming.
So,
1 - I-Frame QP and P-Frame QP are just the quality of certain frames, there's no reason to set them differently, and some QuickSync encoders also let you do B-Frame QP, just not yours for some reason I don't understand.
2 - Quality preset should be quality. QuickSync is a decent encoder, and can handle Quality preset in most circumstances. If you are doing a large resolution at a high frame rate, and you get dropped frames in "encoder lag", then change this to "balanced" or "performance" to stop the frame dropping. Doing so increases your your filesize for recording, or bitrate for streaming.
3 - No. Debug only if it's broken.
Additional:
Your Rate Control Method matters. CQP means you'll get a specific quality on specific frames (I, P and B) NO MATTER HOW MUCH BANDWIDTH IT TAKES. You can learn to tweak this over time. Rate Control Method "ICQ" is better, and "LA_ICQ" is even better. It depends on the CPU you have if they're available options, but if they are there, use them instead. This guy has a great explanation:
https://obsproject.com/forum/resources/custom-parameters-of-quicksync.104/
Alternatively, If you want to know for sure that QuickSync is the best encoder for you, try this:
https://unrealaussies.com/tech/nvenc-x264-quicksync-qsv-vp9-av1/
