UV texturing something big.

If I am going to uv texture something with different parts to it, such as in a land I might want mountains, dirt, and grass. I would need a pretty big resolution. is it ok to use super high rez images? Also, if I have a sword that is all one object, but requires different parts to it, like the blade, the handle, and that weird thing between the handle and blade. as well as teh bottom of the handle, and I want to texture it. Preferably with some reflection just on the blade. How do I do that?

Here is the tutorial I am working with.

For the lanscape you can use fairly high res images, also, if you simply displace the verticies from a plane you can set the UV map from the top down view.

For the sword you can seperate the UV map into different sections by marking it with seams.