Random Forest Satellite Image Classification

Hi, I am going to use RF classification on S-1 images, and I would like to confirm a few things about on how RF works on SNAP. From the posts I have read,

  1. the Evaluate classifier is about training accuracy and not accuracy assessment of the classified image,
  2. So, accuracy assessment has to be done in another software,
  3. The number of the training samples is the number of the pixels that will be used from each vector I have imported (when train on vector is selected) for the training of the algorithm,
  4. RF splits training data to 2/3 for training and 1/3 for an internal cross-validation.
    In the number of the training samples, the number that I am typing is the 2/3 or the 3/3 of the available pixels of each trained class?