Sounds like you have some great ideas for plants already. I'm thinking that you may experience problems with the area being dry due to the tree roots. Maples have very large and extensive roots that tend to surface. Take a look here to understand where the tree roots are and how they grow.
There are some evergreen groundcovers you can plant for winter interest. The biggest problem you are going to have is the tree roots taking the moisture. A few clumps of evergreen lirope should do well. It comes in all green and variegaged types. They should be cut to the ground in late winter/early spring. Click on the pics.
Ophiopogon - mondo grass is a much smaller clumping evergreen groundcover that looks like short clumps of grass. It usually doesn't need to be pruned to the ground and comes in green, variegated and a black color that looks nice against lighter greens and a dusting of snow. Click in the pics.
Vinca minor - periwinkle is another evergreen groundcover that can deal with the dryer conditions. Click on the pics.
If you have a damp spot in the shade bergenia is an evergreen clumping plant that would do well. They can deal with some dry conditions but won't grow as vigoriously.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.