Incar Audio Systems

I would like to know how can I engineer, design (select) & install (set-up) the perfect car audio system?
Like an easy calculation or formula or table (matrix) in order to determine the best (required) head unit, amplifier, speakers type & sub-woofer based on the car or van type.
I looking for just a "Rule of thumb", a starting point, a reference point!
Rule of thumb

I want to buy a car audio system that comes with 2 subwoofers and an amplifier and I want it to be under 400.Any suggestions on what I can get

I’m buying a 2011 Lancer SE (without the fosgate 9 speaker system) next spring. What kind of after-market audio system do you recommend between 300$ - 1000$ and why? (Including subwoofer, car deck and amplifier. Speakers are optional if they fit in the price range.)
Thanks for the links, DA 1-2 B. I’m thinking of getting a sound quality system, for enjoying music, loudness is not really important.

I’m trying to get a better car audio system than my previous, but I can’t remember whether to get 2 ohms or 4- Also, do you know what 2 or 4 ohms can handle in terms of watts from an amplifier…without starting a fire in my trunk….

Can a car audio sub be run from a home amplifier or will it damage the sub or the amp?