Mine are changed as follows.

Let there be Rock = Shoot to Thrill
Whole lot of Rosie = Girls Got Rhythm
Hell aint a bad place to be = Big Gun
Whole Lotta Rosie = Hard as a Rock
Encore Song = Long way to the top

I am pretty sure that is the order they are in. When the game ends it plays a clip from shoot to thrill which fits nicely too.

I forget...It was a live version of something....never heard it personally.....neither have a lot of folks. Heh...

Funny.
It is the end game song that is played when you beat the game. Most people will probably never hear it.
However, Stern chose to put a live version of LTB Rock for the Encore tune. It is recorded softer than the studio versions so it make Encore pretty anticlimactic sounding.
I put "It's a Long Way to the Top" on all the files I have helped people with as the Encore song as it is much more appropriate after all your hard work to get to the end game. It is much louder as we'll.

How about some Hayseed Dixie?

I am not a computer wiz by any means so my question is how hard is to swap the songs out?

Not very hard at all, use Pinball Browser

This is a tough question to answer. For me it was super simple including ripping the songs, converting them, cutting them to length etc. For my wife, this would be about as difficult as performing brain surgery on herself. So it's really impossible to tell you how easy it is without keeping your skill level.

does encore have a unique song to it? I never get even close to ever seeing it, so didn't know. I would want a custom song for that mode for sure.

I put Ozzy Crazy Train for a bit....I took it off but it wasn't too bad. I may try it again but adjust the clip so the beginning of the song is not there...it seemed a little slow and with my poor play I got to hear it a lot as I'd still be on the same song for a couple of balls very frequently.

Not my video, but this YouTube clip explains it pretty well.

Once you change the songs, is it easy to change it back to factory settings with the original songs? Or, do you just reload the current code from the Stern site from scratch.

Yes.