New sound setup in AU1...questions.

[Kevin]

Hi guys, I'd appreciate any help. I don't know a lot about radio installation.

First, how do I gain access to wherever it is under the dash where the speaker wires come in from the left door? Maybe info on the right door too, but I'm not up to that yet. I've got thicker wires to go in which won't merely feed in via inside the door.
I wouldn't mind learning how to get the glove box out too if anyone can tell me. I undid a screw inside it before and the clip moved aside.

There's an MTX Thunder 280 amplifier driving direct to a SAAS subwoofer. The crossover button on the MTX is marked 'in' or 'out' .Do I set this to 'in'?
(Another amp drives woofers and tweeters)
Any suggestions where to put 2 crossovers up the front of the cabin somewhere? Dimensions 26mm high, 127mm long and 73mm wide.

Four 6 disc stackers have an interface between the head unit and the stackers. Is this controller supposed to supply the power to the stackers via the 13 pin leads? Also the stackers are in a wooden box; do the stackers need an earth return?

Thankyou