For the sound:
Code:
/////////////////////////////////////////
sound pl1_snd = <SOUND>;
sound pl2_snd = <SOUND>;
sound pl3_snd = <SOUND>;
sound pl4_snd = <SOUND>;
 
function pl_sound(but,pan)
{
	if(but == 1) {snd_play(pl1_snd,100,10);}
	if(but == 2) {snd_play(pl2_snd,100,10);}
	if(but == 3) {snd_play(pl3_snd,100,10);}
	if(but == 4) {snd_play(pl4_snd,100,10);}
}
/////////////////////////////////////////
panel plSelectionPan
{
	flags = refresh;
	button = 20,20,pl1_hover,pl1_normal,pl1_hover,plSelect,null,pl_sound;
	button = 20,50,pl2_hover,pl2_normal,pl2_hover,plSelect,null,pl_sound;
	button = 20,80,pl3_hover,pl3_normal,pl3_hover,plSelect,null,pl_sound;
	button = 20,110,pl4_hover,pl4_normal,pl4_hover,plSelect,null,pl_sound;
	button = 20,140,pl4_hover,pl4_normal,pl4_hover,plSelect,null,pl_sound;
	button = 20,170,cancel_but,cancel_but,cancel_but,plSelect_cancel,null,null;
}
/////////////////////////////////////////


Yep, you need to use a tga with alpha channel (Or setting transparent and the alpha value of the panel, though I'd recommend using an alpha channel)

I don't know much about the model formats. I think you should use mdl7, but I dunno.

Nighthawk Arts || NHA RPG Templates