Generally, Macs are not easily upgradable, no. Sometimes they are, but usually not.
Probably not.
Laptop graphics cards are generally considered to be impossible to upgrade.
By upgrading the graphics card.
Apple sells only only one version of the Macbook Pro 15". You can upgrade the processor, ram, hard drive, and display if you wish. If you are using this Macbook as a student, I would recommend you get the Macbook Pro 13" base model and save yourself $600. It is all a student will need. However if you are looking for the best laptop you can get for your own use then the 15" is the best of the best. Unless you are doing graphics and or video editing you have no need to upgrade it. Only you know what you need.
You can upgrade your laptops graphics. You will need to see what type of graphics cards your computer is compatible with a choose one to your liking.
You cannot. With the introduction of the MacBook Pro Retina line in 2012, it's not possible to upgrade your RAM as you could with previous MacBooks.
No you can't.
No, the graphics chip is embeded.
Yes, you can. The motherboard is equipped with a PCI-e port so you can plug in a graphics card.
No both graphics card must be the same.
A MacBook will run Mac OS X 10.6 (Snow Leopard). If the MacBook is currently running 10.5 (Leopard) a copy of Snow Leopard will need to be purchased.
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...