How do I visualize data for a natural language processing project?
I'm not an expert but let me try to think with you. What's your vocabulary size?

I think certainly starting with a small machine learning model is a good idea, but I think that a decision tree would quickly suffer with even a medium-sized vocabulary. You would need a huge tree to do anything. So I think I would start with pretrained word embeddings, and use a small neural net to predict the starting point. This helps, because words that are close in meaning have similar vectors, and the decision tree wouldn't be able to use that kind of information.

Your suggestions for histograms don't seem bad, but you would have a histogram that is as wide as your vocabulary, which seems like it defeats the purpose of visualizing it... If you went with word embeddings, how about using a technique like UMAP to plot the questions and articles in 2D?