In C# should I use uint or int for values that are never supposed to be negative?

Answer 1

See here for the previous answer.

Answer 2

Short answer is No. You may want to implement as below.

private int _length;
public int Length
{
    get { return _length; }
    set
    {
        if (value < 0)
        {
            throw new InvalidOperationException("Length must be always positive. Please make sure the value is positive value.");
        }
        this._length = value;
    }
}