The amp is rated at 15 watts. We use Rodney's speakers here at the shop for replacement speakers and they do sound good although I am not sure of the manufacturer.
To install the wiring properly the dash needs to be removed as the wiring for the slider switch runs from the rear of the radio up behind the a/c vents and across the frame to the connector block located on the upper left shroud. from there it continues up the a-pillar and under the headliner.
It is possible to run the wire without removing the headliner but you will have to remove the left sunvisor - the standard dome light wiring is held in place with nylon clips attached to the roof of the car.
I use a "pickle fork" tool designed for removing trim tabs (found at your local auto supply store) to remove the a-pillar. There are two tabs on the a-pillar attached to metal clips along the top of the door which may break if you don't remove the trim piece properly. use the pickle fork from the OUTSIDE of the car, insert it between the plastic a-pillar and the frame and lift up GENTLY - the a-pillar will slide out toward the inside of the car. The a-pillar is attached to the windshield side with two plastic clips which always break (we have them here at the shop if you need any for replacement)........then you will see the dome light wiring running up the side encased in a plastic sleeve held to the frame with plastic tabs. just pop the whole sleeve loose and follow the wiring to the connector on the shroud - that's where you plug in the replacement wiring.
The dashboard is not that difficult to remove but you will need a torx bit and a 7 mm socket and a 10mm socket........you can unbolt the dash and roll it over toward you and have enough room to run the wiring without totally removing the dash.
And, yes, we use SEM paint to paint all of the interior parts here at the shop.......I painted my gray dome/slider control to match my tan interior and it looks just like all of the other tan pieces inside.......
Hope this helps..........if you need any more info, you can call me at the shop at 510-233-4376 and i'll step you through it - I have done this MANY times, on my own cars as well as customers cars.......