1. it is better to leave oak leaves in garden or remove.
2; for oak leaves not in garden I rake and shred, then put in compost… they are slow but do compost. Any problems with this?
3. Norway maple leaves from neighbors yard. These leaves often have black growth on them. Is it okay to compost.
There is a saying that oak leaves take 10 years to break down. (Who kept track?!) For this reason, many gardeners prefer to dispose of oak leaves through the municipal yard waste program. While it is true that they take a long time, shredding oak leaves produces useful mulch. The leaves are acidic, but are a useful ingredient in making leaf mold. The waxy texture of the leaves comes from the lignin, a substance that causes interaction with nitrogen in the soil to leach and bind in the soil rather than feeding the roots. So, while not adding to fertility of the soil, oak leaves add texture and mulch to protect bare soil.
Norway maples can be subject to a black spot virus. For a time, gardening advice articles recommended separating these affected leaves, but that is a tedious task. Then we learned that the virus is airborne and no protection or treatment would make a difference, and that the virus seemed to attack only the one species of maple.
You are being a concerned and conscientious gardener, but be assured that your practices are causing no harm. And you are helping a natural process to move a bit more quickly. Continue to compost knowing you are being helpful.