Newbie, 2015 Mazda 3, high pass filters?

Hi!

A warning now, these are probably embarrassingly newbie questions.

I am going to be installing some Infinity Reference 6500cx component speakers in a 2015 Mazda 3. I would like to make a home made high pass filter for the tweeters so I don't need to worry about wiring through the door. (There is full signal wiring going to the existing tweeter location, I am not running the tweeters through the supplied crossover).

Using a 4.7uf Capacitor for the 3ohm tweeters it would make a 11300khz high pass filter, is this too high/low for the crossover freq?

Secondly, not really understanding the science behind the capacitor, as the low freq's are 'blocked' by the capacitor, does it build up a charge in the capacitor? if yes, where does that charge go? does it dissipate with heat? is it such a negligible amount that it doesn't matter?

Thirdly, some high pass filters has a resistor in between the + and -, what is the purpose of this? can I safely do without it?

Fourthly, Is a 50V bipolar cap adequate for the task?

Thanks very much for your time.

Why not mount the crossover in the car instead of the door. Then you can easily run the wires from the tweeter output of the crossover to the tweeter.

Use 100 volt capacitors.

I still have the issue of running the wiring to the woofer in the door. I didn't want to stuff around trying to route stuff through the dash and through the door molex.

Also, why do you recommend 100V? I can't imagine the signal would be anything over the 14volts the radio is powered off, is this a 'just in case' thing? Or is it that instead of the capacitor rejecting or blocking the low level signal, it is actually absorbing it and building up charge?

Use the OEM wiring that is already going into the doors. Crossover in the car, woofer wires of the crossover to the wires at the radio or factory amplifier. Tweeter wires of the crossover directly to the tweeters.

I have seen several failures using 50 volt capacitors. Never with 100 volt device.