Questions about certain fields on Common App

Honors:
What counts as academic honors on the Common App (examples)? Do awards won competing in science clubs count?
Extracurriculars:
How descriptive should I be when reporting my extracurriculars? Do I write in complete sentences or can I write in fragments? What happens if I don’t have room to fit everything about the activity in the box?
Is it okay if I have an overlap between extracurriculars and honors (i.e. I’m part of a club, and I won a few awards for it, do I fill out both parts?)
If I did research as a class, should I report that as an activity on the Common App or is it not necessary? (if I do this I’ll max out the number of slots for the activities, and I want to leave that slot open for any other possibilities.)
Reporting scores:
For AP tests, should I report the AP tests I am planning to take or is that unnecessary?
Do I report the Calculus AB subscore from the BC test?

There are no hard and fast rules. The space is limited, while you can list a club as an activity and any honors received as honors, what really matters is whatever is important to you. Don;t fill boxes just to fill boxes. You do not need to use complete sentences. I’m of the opinion that if you can’t get your point across in the box, you need to edit it do you can. It’s extremely rare to find an activity / honor that needs so much explanation that it has to spill over into another section. Also note that names should not drive your selection. e.g. NHS is neither national nor an honor (unless you’ve received an honor as a result of NHS).

AP scores are optional.You can list any/some/all. Again, the space is limited. If you have so many APs that future ones won’t fit, omit the future ones. If you have the space, you can list future ones, but it’s not necessary. Similarly, you can list a subscore, but it’s not necessary.

There are no rules. You should organize this to best synthesize your accomplishments in a clearly understood manner in a sensible context. So for example, if you made All State whatever, that should be a part of that EC description. Honors are better suited for stand alone awards. Also remember Honors in the Common App only apply to academic honors.