If you're just changing the fan, no. If you're changing the entire heatsink, yes.
Thermal compound rests between the CPU (heatspreader) and the heatsink, and is used to improve heat conductivity in areas where the two metal surfaces aren't completely flush.
Technically it is possible but it complicated and most likely expensive. Graphics cards are not made to be readily switched in laptops so the entire laptop would need to be disassembled and things like thermal compound (used on heatsinks) would need to be reapplied. It is most likely not worth the hassle.
You can use laptop broadband to connect to the internet. T-Mobile and other providers can help you find the answers you need. technologies are always changing.
You will need to go to the manufacturer's site to obtain the schematics for your particular unit. Changing a sound card may be something you need to have a professional do for you.
Low thermal conductivity!
Garage band! I'm not sure on the changing of voice though. I haven't been on it for a few years so they may have improved.
Its depend upon the your purpose and idea. For what purpose you are going to buy laptop. gaming and business laptop need high RAM.
you dont, if your laptop supports it you dont need the dongle
no you dont NEED it, but you do need a router(wifi connection) in order to use the internet on the laptop
an extention cord...
To carry your laptop computer safely and comfortably.
yes but you will need a thermal wetsuit