You ca nplay any given scale al across the fretboard on even one string if you like. The normal electric guitar (with 24 frets) gives you 4 full octaves. you can transpose it to wherever you like aslong as you play the same notes - else you will leave a specific key and enter another key.

Basically i would say you get the guitar, get used to the feel of it, for an electric feels alot different to a classical (the stings are thiner, the space between the strings is smaller, the neck is smaller, etc). Noodle around abit and play a few things that come to your mind regardless of the theorethical background. dont get yourself tied up in too much theory - concentrate on your play and feel first :)