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Would changing the size of texture maps help anything, like some of the texture maps are like 4000 x 5000 and are like 20 megs each (OUCH!) so would reducing the size to about half do anything?

There's no need to use textures that size unless you intend on rendering TO that size.
For example, if you're rendering a face at 1024x1024 pixels, you'd need at least a 1024x1024 image map for it,  so the detail is there, but anything larger isn't going to benefit you any.
So, if you have an 800x600 render, with 4000x4000 textures, you're just wasting memory and render time, with no advantage at all.
To answer your question, most definitely YES, smaller image files will use less memory.