He or she will usually be happy to do that for you, and if your hardware doesn't support Linux can usually locate and install what's needed. Linux supports a whole lot more hardware than Windows or Mac, but some hardware designed only for Windows may not work with Linux. If you follow the suggestions above, using Linux is mostly like using any other desktop system - point and click. You can gradually learn more about the system but you don't have to know much to get started using Linux productively. However, if you insist on installing and configuring Linux yourself, there may be a steep learning curve.
Installation can be tricky, and configuration is at the heart of system administration.
That's up to you. All it takes is a little initative to find out where you can get Linux preinstalled or to give that nerdy kid down the street a phone call. If you lack the initiative to do that, you had best stick with Microsoft Windows or Mac. Generally, experienced Linux users will be helpful if you ask them for help. A small but significant percentage, however, have an elitist attitude.