If you’re just starting now, don’t practice with the electric unplugged: may introduce bad habits about not muting strings correctly, etc. If you need it quiet for night practice, or are still too n00b to feel good playing it out loud (I know I was when I started), then get something which allows you to play from headphones. See this thread for some good discussion and options for low-volume amps.
Or, if you’re not yet ready to pick an amp, what I did when starting was to get myself a Boss GT-1 effects box. It allows me to play/practice with headphones, have many different “patches” for different sounds, and it’s fully customizable. Plus, it has a USB audio interface, which is great for recording; later when you get an amp you can still use it as your stompbox.
Coils: I have an HSS strat as well; when I started with Justinguitar I used almost solely the middle, single-coil pickup, as it sounded best for open chords to my ears. It was only when I got to the lesson on power chords (and adding some distortion) that I started using the humbucker pickup on the bridge position.