I’m glad it’s working! 

No, your model will be trained on 354 batches, each containing 100 images (as specified in the batch_size of your train_loader. Since you are splitting your training data into training and validation, this number is a bit smaller than 39209//100.

Prec@k sounds like it should give you the precision for k predictions, which is calculated as TP/(TP+FP). However, since you have multiple classes and looking at the code for accuracy, it looks like it’s calculating the accuracy for the top k predictions.
As you can see, the value is scaled by 100 and its batch size, so that it gives you already the percentage.