Answer:
Buying a good laptop, especially when on a budget, is not easy thing. There are quite a few brands on the market, but the problem stands on the fact that you need one that will allow you to fix it, when the need arises, without having to resort to the company´s maintenance services, which cost quite a bit of money.
In order to do this, and in answer to the two questions you have here, you would:
First, narrow your search to companies who offer online free instruction manuals, and how-to-fix-it yourself manuals. There are companies that will either post these service kits, and easy-to-follow manuals online, free of charge, for you to maintain your computer, without having to either buy an extended warranty, or take your computer to a service center, or they will also post videos in different websites, for maintenance instruction.
Second, from the different manufacturers that you could research, there are two in particular that will offer you the services that we mentioned on the first part of the question, these are Lenovo and Dell. Among the many good things of these two companies is that, aside from their computers being really good, they also offer instruction manuals online for free, and they even offer material on how to assemble and disassemble the computers and also information on computer parts that might be available on the market for a cheaper price, and which would be compatible with their computers.