Ah, climate control is a system whereby the car maintains the temperature which you set on the panel (digital panel in the E46). The manual A/C option is a single button that turns A/C on or off, along with three rotary dials (fan speed, fan direction, temperature). CC is the better system, unfortunately ours only has A/C and the retrofit process just isn't worthwhile (dashboard out job).
As for Audio, depending on what you want out of the system, you might be better off either getting the double-din relocation housing (moves the Climate/Aircon controls to the bottom, where you'll currently have a sunglasses holder). This opens up a world of options ranging from "Chinese" OEM looking units, to third-party "premium" manufacturers like Parrot (we have the Parrot Asteroid Smart system installed, after trying a cheaper Chinese unit - thanks for the recommendation mrk!)