If I where to hook up a motorola razr to my computer using it's USB cord, which motorola mobile phone tools should I download that will let me plug it in and go onto it using that motorola mobile phone tools?

What do you mean, which one? There is only one current version of Motorola Phone Tools, version 4. The various choices on the Motorola store are just variations on whether you need a USB cable or a CD. Assuming you already have a USB cable, just download MPT from http://www.store.motorola.com