My First Tacoma & A Bunch Of Question...

I just got my first Tacoma last night. It's a '98 PreRunner Xtra Cab V-6 TRD Off Road, 160K. First off, am I suppose to have a locker? I thought the V-6 TRD's were suppose to have them stock, but I don't, there's just a black panel where the button is suppose to be.
Second, there's a small hole in the muffler and when I crawled underneath to look at it, I noticed that the exhaust pipe "expands" after the cat, like a cat back system. Is that stock or would that be something that a previous owner would have installed? If it's aftermarket, should I leave it and just install a matching high flow muffler, or should I just put it all back to stock? If I do go with cat back/high flow, is there anything I need to do with the intake to make it work better/correctly with the modified exhaust?
Also, the insulation under the hood is starting to fall down and is looking pretty ratty. Can I pull it out and throw it away, or do I need to replace/repair it?
I couldn't get much info from the owner, as it was a 19 year old kid who had no clue about anything. He rarely drove it and the truck spent 90% of the last 7 years parked out under an oak tree so it going to take probably 3-4 days to get it cleaned up. Not to mention someone installed a "clear bra" on it and it looks horrible...dried, cracked, dirty and it only wants to come off 1 millimeter at a time. Oh well.
Thanks for you guys input, I've already learned a lot from this forum.

 

If there is a button then you have elocker, if not then you don't have it.
The factory muffler is huge! About a foot and a half long. Maybe 2 feet? Usually aftermarket mufflers are a little smaller. You should be able to tell by the tip and the exhaust pipe. Also aftermarket mufflers should be louder than stock. But with the hole in it, you might not be able to tell. Some pictures might help us figure out what you're trying to discribe.

The insulation can be taking off and thrown away.