Yes, you should pass the same params to tokenizer that you passed during training.

AutoModel won’t add the heads (classfication layer, LM head etc). Use proper AutoModel classes to get same weights and params i.e AutoModelForSequenceClassification for classification model, AutoModelForCausalLM for causal LM’s like GPT-2 etc

You can load the saved model using just AutoModelForSequenceClassification.from_pretrained, it’ll load the config itself. You should pass config explicitly when you want to change something in it.