There is virtually nowhere that you can find a new Macbook for that price. I would suggest going to eBay and searching for one there, but again, it is EXTREMELY rare to find one at this price.
$50
Macbook Air.
First thing you do is save your files to discs. Next, deauthorize you account from your old computer. Then, import your files to your new MacBook. Finally, authorize your account from your new MacBook.
A Macbook Pro is the best new Apple laptop. Ram is something that goes inside of the computer to make it run better. But yes, any Macbook would be good for a new user.
No.
Nope, the aluminum case on the new Macbooks are unibody, so they are not just the cover. You will have to buy the new unibody aluminum macbook to have that casing.
New Macs all have the same software installed. If you are referring to Garageband (See links below) then yes both the MacBook and MacBook Pro have it installed.
Yes. In fact, it is better than some MacBook Pros.
MacBook Air
No, a brand new MacBook Air is between $950 and $1000 US. A refurbished one is usually around $100 less.
If you have a new macbook pro with the metal body case, no. If you have an older macbook pro, you can use a coin to turn the lock on the bottom of the laptop to remove the battery.
No! The processor is soldered with the logicboard/motherboard. they only way to change/upgrade the processor of a macbook pro is to do it when you purhase new macbook pro. hope this helps...