Check over on toyotapartssales.com website, I think you should be able to pull up the parts numbers there. If not, you can give them a call and ask for help. I've dealt with them many times and they've got great customer service and really competitive prices too.
It looks like there is no CD player. The space above your radio looks like that is where the CD player should be. Go back to the $tealer where you asked your question and have the moron show you where you would insert your CD if you indeed do have one.
The $tealer could well be right. With all the heat the engine compartment generates, the battery could be dead after four years. I make it a point to replace mine every 4 years just to be on the safe side and for piece of mind. If you don't mind paying extra for one, look into getting an Odyssey red or yellow top battery. Doesn't need water for the lifetime of the battery and won't leak too. It uses a gel based medium instead of water.
What does your owner's manual say? I think your 4Runner has the 4.0L V6 like the '05+ Tacos so I would suspect that it needs only 87 octane. You can fill it up with 91 octane every month or so as a treat for your engine, that's what I do.
I would consider changing out the front and rear shocks, all the bushings including sway bar, steering rack, end link, etc. Maybe even think about replacing the rear leaf packs too, it couldn't hurt.
I would not use 95 octane unless the owner's manual specifically states that you must use it. There are no benefits in using higher octane unless your engine is pinging or knocking. Higher octane is beneficial if you are turbocharged or supercharged. Why waste money on higher octane if you don't need it especially when gas prices are so high?
I would personally go synthetic and you can go longer with your change intervals too. I'm not sure where you live, but I would suggest getting Mobile 1 or the Castrol synthetic made in Germany. I believe the ones that are made in Germany are 0w-30.
Have you changed your fuel filter yet? Check for any loose vacuum hoses, especially those under the throttle body. Try cleaning for your MAF sensor too, that may help.