A search on 'abolishment', for example, will pick up 'abolish', and 'abolished'. This is not the case for all potential search terms. For example, a search on 'abolition' does not search 'abolitionist', nor does a search on the latter search 'abolitionists'. I'm not sure how this differs from a straight search.
Right truncation is automatic.
National Geographic Keywords in title, related topics and contributors. Best to use Advanced Mode, and use the Browse feature.