The tip of something: I might settle for (object) 尖 cìam.
Extension (phone): Interesting one. Off the top of my head, I would probably phrase it interrogatively as 電話線幾號 tìan-ŭa-sŭaⁿ kūi-hò or just 幾號線 kūi-hò sŭaⁿ (if the reference to a telephone is already obvious from context).
Extra: 復加 kòh-kàe. So, your example sentence would become something like this: 伊人復加送我五本册。 i-lang koh-kae sang wa gO pu chaeh. (“On top of that, they also gave me five books.”) I would personally reserve 另外 leng-ua to specifically mean “separately” / “outside the existing scope”, which has a subtly different meaning from “extra”.
To decorate: 擺秀 pài-sûi (mind the provisional character for sûi).
To defeat someone, beat someone at something: I would settle for just 撲贏 phàh-iáⁿ. An alternative that I hear quite often is 撲倒（伊） phàh-tô (i).
To delay: 拖（較）久 thūa (khā) kû.
Of course, I am aware that there are much more elegant ways to say them in “pedigree” Hokkien, but in a daily “on-the-street” context, the average listener would probably find them contrived and artificial (to note that my usual standard points of reference are coffee-shop conversations among old Penang Hokkien uncles, currently in the 60’s to 90’s age group, and typically (but not necessarily) Chinese-educated).
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