2 project ideas: is Arduino right?

I have 2 project ideas that im considering getting an arduino for, but i'm fairly new to this kind of technology and not sure how well it will work, or what to expect.

First one is fairly simple:
It will be to simplify the remote starter in my car. as it stands now, you have to have the car running, hold the break, apply the handbreak, release the foot break and push the unlock button on the remote if you want to be able to start it later. if at any point something else gets bumped, including opening a door after its set, it disables itself again. when the starter is in an automatic, you push the button and it starts. simple as that. What im looking to do is set the starter in automatic mode and have the arduino manage the standard start procedure. basically how i want it to go is having the arduino get power from the "on" signal from the starter and start the code when it receives the starters "start" signal on pin x. (that signal will be 12v so it'll may have to be stepped down?) after that it will compare "handbreak on" on another pin and "in neutral" on a 3rd. if those 2 conditions are met, it'll output a "clutch pressed" signal followed by "start engine" then a moment later "release clutch"

so in short when pin 1 = on, check pin2&pin3 = on, then output pin4, output pin5, turn off 4+5. (pin #'s are just examples)

is there any foreseeable problem with this? and can the arduino take a 12v input? or give a 12v output?

the 2nd idea is a little more complicated.
I've seen a ton of videos of people with rbg LED's flashing to music, but i havent seen any that do it how i would like. the colors always seem random and uncoordinated. my idea to make the colors fit the music better is to assign a series of preset colors (yellow, blue, green, purple, etc) to different notes. but more then that, i want to have the arduino read the music and pick out what notes are loudest so it lights up to the part your brain is following. in a drum solo the low pitch kicks would be one color, and the higher pitch snares would be another color, then when the lead part comes in, itll flash along with it instead.

i have less of an idea how to make this happen or if it even can. its probably a coding nightmare and i dont even know how to put a sound input onto one of these things. any help here would be appreciated, or maybe point out another product that already does it?

I think you'll find that the reason for all those extra steps in the manual installation is for safety - to ensure that the remote starter will never be used when the car is in gear. An automatic usually has a neutral switch which makes this much easier to do safely. There's no reason you couldn't install your own neutral switch on the gearbox linkage, if you don't mind groveling around under the car and doing some fabrication. Otherwise, I suggest you think twice before disabling the safety features.

There are some projects in the playground which show how to implement a frequency analyser and produce a graphical display.