Weird...
positive, extra, additional
Happy is a positive emotion and describes someone that feels that positive emotion. 5 synonyms for happy are: joyful, cheerful, merry, pleased, and delighted.
delightfulgoodhappylovelywonderfulawesomewowjollynicebeautiful...just to name a few!
Castle
Skinny of course
There are no synonyms. An equivalent phrase could be absolute values of non-zero numbers. Remember that 5+sqrt(3) is a positive number, so your "synonym" must cater for that.
Unique Special One of a kind
helpful, positive, useful, practical, valuable, productive
clairvoyance divine madness
Positive:+plussumadded toadditionaddandmore thangreater thanincreased byNegative:-minusless thanlessdifferencesubtractsubtractiondecreased by
confident, positive, aggressive, forceful, emphatic, insistent, feisty, pushy