Nikon isn't the only major camera maker around.. Canon, Minolta, Pentax and previously Olympus makes good SLRs.
The Nikon FM2 is a fully maual camera, good if you like manual and want to start out from the very basics of basics. However, if you occasionally want to take those point n shoot type of pictures (ie just click and snap without worrying about exposure etc), then it would be better to go for a autofocus camera. Using an autofocus camera gives you as much control over the camera as a manual camera, with the added benefit of auto-everything when you need it.
Lenses can be broadly divided into two types: zoom lens and prime lens. A zoom length means that the focal length is variable, e.g a 70-200mm zoom, or a 17-35mm zoom. If you've played with your friend's F75, most probably you would have used either a 28-80mm or a 28-100mm zoom lens. Standing in one spot you can zoom in and out using the zoom lens (ie picture you see get bigger and smaller).
A prime lens on the other hand has a fixed focal length, eg. 50mm, 24mm, 180mm. It's fixed, so if you want to get 'bigger' or 'smaller' picture, you have to physically move yourself to get closer or further away.
Zoom lenses are more convenient, but prime lenses are lighter and usually much better optically speaking than a zoom of around the same price.
Most cameras nowadays come with a built in speedlight (flash). However the FM2 you are looking at do NOT have a built in speedlight, so you need to buy a speedlight if you want to take flash photography. Most people buy an external speedlight and attach it to their camera because either the built in flash is not strong enough, or they need to tilt/swivel/bounce the flash (don't worry about this yet).
I strongly suggest you borrow some basic photography books from the library to learn more, especially things such as exposure etc. It would help you alot in the future and enable you to take better photographs.
