1.) Easy one. What game came with Super Mario Brothers when you bought it with the NES?
DUCK HUNT came with mine, but DarthRacer is right. The first one just had mario.
2.) what changed when you beat the game?
After you beat the game, you're allowed to play it again. This time around all the mushroom guys are replaced with the black armored armadillo guys.
3.) What is warping and one which levels can it be done?
You guys said it. Warping is when you find a secret area of the game where you find a set of pipes that warp to different levels (8 total). In level 1-2 you can run over the green pipe at the end and find warp pipes to levels 2, 3 and 4. In level 4-2 you can find a secret vine that takes you above ground to 3 more warp pipes that can take you to 6, 7, 8. I also think in 7 you can warp to 8, but I'm not 100% sure.
4.) What's the quickest way to beat the game (warping that is)?
Quickest way to beat the game: 1-1, 1-2, 3-1, 3-2, 3-3, 3-4, 4-1, 4-2, 8-1, 8-2, 8-3, 8-4 (taking all the proper warps along the way)
5.) What's so special about level 3-1??
Darthracer hit the nail on the head. I've never been able to beat the game without doing this first (you'll notice 3-1 is in the list of quickest way).
6.) How do you "Slide Though the Wall" and what does it result in?
On level 1-2 there is a green pipe that normally takes you to the surface and to the end of that level. The three bricks closests to the pipe are the trick. You break the left two bricks and leave the one closest to the pipe. You then scooch to the end of the pipe, jump left and then pull right in mid air, hitting the remaining brick as you go. It takes a long long long as time and I consider this feat the second most difficult trick. After you gotit right, you will SLIDE THROUGH THE WALL. And by that I mean you will slide to the right through the brick wall and into the normal warping room that normally takes you to levels 2, 3, 4. There are no numbers on the pipes though. If you jump around in that room, the numbers will show up and you can warp as normal. If you want to be silly, you can go down the left pipe or the right pipe to enter a level called "-1". -1 is a swimming level and it's a dead end you can't get out. I think if you down the middle pipe, you go to level 2 (but I don't remember).
7.) How does one go about getting "Little Fireballs"??
Little Fireballs is the hardest trick in the game. I think you can do it on any -4 level (1-4, 2-4, 3-4 and so on). I've only ever done it on 3-4. This is how it's done: You need to be big and only big (no fireballs). Next you need to get to the end of the dungeoun where bowser is jumping up and down and throwing hammers. You need to sneak under him or over him without getting it (being small won't do the trick). As soon as you get to the right of him (towards the golden axe), he will start to chase you on the ground. You need to wait un til he's just about to get you. Then you jump and touch the golden axe and you have to time it so that Bowser touches you at the same time. So you touch bowser's head and the axe at the same time. This would normally make you small. Instead you get this "fuzzy" look about you as if you're in the middle of going small. You then talk to the little mushroom chich still in this fuzzy state. When you start the next level, you'll be big. But when you hit the first mushroom block it won't be a flower, but a mushroom. You grab this mushroom (you'r big) and it makes you small. The next mushroom block / fireballs flower block will be a fire flower (you're small now). You grab that fire flower and guess what? You have fireballs and you're small (little). You're wearing the orange and yellow jump suit but you're little. When you hit the fireball button, you'll see a single frame where you're normal size just as the fireball comes out. It kind of looks like your head is swelling or something.
Anyway, those are all the tricks I know. I guess when we were 10 and 11 there just wasn't anything better to do than to try these tricks and crap. I've played t such much that 17 years later it's still programmed into my fingers. I was playing like it was yesterday. I felt like I was 10 years old again except the TV was a couple of times bigger. LOL