I can't really answer #1 or #2 since I don't have a PS3 of my own. Though I can say aside from being a huge detriment to society in general, Walmart is one of the last places you would want to go to get AV cables. Check out the website Monoprice. The only hitch with them, is they have flat rate shipping which starts at about $6, so you want to order enough to make it worth the shipping.
Moving along... Aside from updates for the console's firmware, if you're not interested in online gaming, there's little point in connecting them to the Internet. If a game needs a specific version of the console software, it will come with an updater on the disc. Of course with the 360 you can download game demos and other stuff on Xbox Live, and Sony has something similar for the PS3 and PSP. But you shouldn't be required to connect to the Internet to play a non-MMORPG type game.
#4: Saved games are part of the purpose of the hard drive, though I do believe you can still use memory cards on the PS3. Unlike the 360, you can use cheap and easy to find SD memory cards however IIRC. But the hard drive is also used for downloaded content like game demos, additional online map packs, you can store music and movies on it to watch later... Things like that.
#5: It kind of depends on the experience you want. There's always going to be loads of accessories sold, but really all you should need is the console, a controller, and a game disc. It's been that way since the beginning with game consoles really, but some people who are really into racing games might want to buy a special controller made up like a steering wheel for example.
#6: Seems to me you already know more than most people do going in buying a game console. AFAIK the PS3 hasn't had any major manufacturing defects like the 360 with it's infamous red ring of death issues. I would just recommend AVOIDING using the PS3 as a blu-ray movie player. The bluray drive in the PS3 is unique in that it can also play PS3 games, something stand alone bluray players cannot do. Stand alone players will also eventually come down in price, but there will likely be a floor on the price of the PS3. So, save your PS3's drive for playing games would be my suggestion.
So I have been looking at the PS3 for a few days, and it looks like a good system. However, this is my first game console that I would own(I'm 18), I have played on family and friends n64, xbox, and ps2, so I have somewhat of an idea how these things work. I do have a few questions though...
1. Controllers, I see two USB ports(or similar) on the front of the unit. Are you limited to only two controllers? Can you get a USB hub of some kind to add more? How many controllers came with the unit?
2. Connectors, It appears on the back of the unit there are a few connection points, the TV I will be using does not have the HDMI inputs, so I would have to use standard A/V cables (L/R/V or white/red/yellow). Does the console come with the necessary cable/adapter to use this setup? If not, how much, say at Walmart, to purchase this?
3. I have heard some things about these new consoles that are internet enabled. If I did not want to play multiplayer, is there any reason to use the internet capabilities? Will I get locked out of a game for a possible "licensing" conflict?
4. What is the purpose of the hard drive? Save game data? Or are there the memory cards still?
5. Are the units nowadays still as simple as insert a disk and play the game? It just seems like besides the game, you have to keep buying more "stuff" (Like the iPhone/iPod touch). Is this true, and will it effect game-play?
6. Over all, what would be some things I should know about the PS3?
Sorry for all the questions! I really am new to all this....