Chassis.
Deaf
tireless
The adjective would be invincible. (unbeatable)
One art involved with handwriting is called calligraphy.
invisible
There is no associated "philia" for cars (autophilia is self-love). They are usually called car collectors or car buffs.
There is no one-word substitute in English for "son-in-law."
The word you want is florist.
The action is to "customize" or install options. (Another word for the production of extras is the "aftermarket.")
Sportsmanship is a word substitute for spirit of game
The word metalworking is one word.
eat, use
One possible substitute for "their" is "his" or "her" depending on the gender of the person/people being referred to. Another substitute can be "its" when referring to a non-human object or entity.
The word that works is idiot.
Elevate
Traditionalist
Omnipresent