Tagging “don't” (or really two tokens, “do” and “n't”): the verb 'do' is not considered an auxiliary in the PTB scheme in the sense of having a special tag. If it’s a present form like “I don’t do X” then the first ‘do’ is VVP and the second 'do' is VV (a base form); if it’s an imperative like “Don't go!”, it’s VV for both verbs (imperative is not considered present). The negation ‘not’ and also the form ‘n’t’ is considered adverbial (compare ‘very good’ vs. ‘not good’ – both modifiers are adverbs). As a result, it’s tagged RB.

Titles of books, films, etc.: tokens are considered NP or NPS if they are capitalized, but function words are tagged as normal. So for Starship Troopers, both words are considered ‘proper’ and tagged: Starship = NP and Troopers = NPS. But for “Beauty and the Beast” we get: NP, CC, DT, NP

In cases like “more interesting”, we have two tokens - ‘more’ itself is tagged JJR, but 'interesting' is still just a normal JJ. If you're counting comparatives in the corpus, counting JJR still gets you

No verb should have -ing in its lemma. However, nouns ending with -ing should keep the -ing in their lemma. Some words can be both nouns and verbs; categorize them based on the specific instance.

• writing_VVG beautifully has the lemma write
• beautiful writing_NN has the lemma writing

If a multi-word construction has been lexicalized into one word (i.e. rapidly-growing rather than rapidly growing, then it must be treated as a lexicalized adjective or noun rather than a verb. Most often, these become JJs, such as

• a rapidly-growing_JJ plant

Lexicalized nouns exist too, like

• the constant egg-laying_NN

The lemmas of these words keep the gerund, i.e. egg-laying and not *egg-lay.