im having similar problems.
i also installed iPC 10.5.6
i have no wireless (ethernet is fine), very glitchy, i cannot download anything or else my computer freezes and i also have no audio.
i was also wondering if you are still able to download kexts/drivers without having to install the os again, because im not going to lie that was the worst 14 hours i spent working on my laptop in a long time
btw i have a HP HDX 16