Acronyms (stringing the first letter of a series of words together to create a new word or phrase, like SCUBA). Anagrams are words or phrases that contain the exact same set of letters as another word or phrase. Palindromes are words that are the same word forwards and backwards (racecar). etc.
the skinny guy is Waluigi. Stupid name, but entertaining. Makes sense I guess that Luigi has an arch nemesis...? He'll be in the upcoming Mario Kart it looks like.
Mmm, the joys of numerology. Look for a pattern and magically the pattern emerges!