Cerwin, I'm not sure what you mean when you say,
...Cow maure is better then horse...
I suppose what nutrients you want to add to the garden would determine which manure you would want to use if that is a concern for you . Manure should always be well rotted. This guide about manure content should be helpful.
More manure info.
Guide to composting horse manure:
Adding shredded leaves to the soil to decompose over the winter is a good thing. As to the question of tilling or not to till, this site explains alot about what tilling does to soil structure and organic material.