I upgraded an old Acer aspire 5630 laptop processor (C2D) to the max that it can handle recently. It is pretty straightforward to do. It just had a flattened piece of copper pipe with a thin spring loaded plate for a heatsink.

Once inside the case, it was just a matter of removing a few screws. A quick clean up of the plate thermal area. In with the replacement processer. Apply some thermal paste and put the plate/pipe back on.

If you are in any doubt, Acer service manuals are easily found online. They show how to do this and more.

Edit: The service manual will also give you the full spec of the motherboard and any variants for similar models. You can see from that which processors the board/s can handle.

Yes, but I don't recommend this action for anyone who is not very familiar with laptops.

They have a lot of screws and many of them are hidden. If you don't remove one something will bend and most likely break.

Assuming you manage to get everything apart correctly, you will then need to remember where everything goes back.

Bear in mind I used to repair computers for a living. Last CPU upgrade I did required a replacement keyboard. The parts are very delicate and do not allow any flex at all. Things that you wouldn't think would be a problem go wrong fast.

Not that it's impossible, and a service manual would help. If you want to proceed it's not for the faint of heart. Your mileage may vary, of course, and some systems are far easier than others.

It's generally not worth the time, effort, and research required to upgrade a laptop CPU.

Some laptop CPU's are soldered directly to the motherboard making upgrade nearly impossible.

A performance increase of more than 10-20% is unlikely for an upgraded laptop CPU. However if you get a new laptop/desktop, performance gains of 100% or greater are likely.