1995 GMC Sierra Headlights and brakelight/rear signals

Electrical problem
1995 GMC Sierra V8 Two Wheel Drive Automatic 65 000 miles

Hi there,
On a recent vacation, our GMC 1500 lost both low beam headlights at once (when you toggle between high and low beam, high works fine but low doesn't. Because both sides went out at the same time, I suspect that it has little to do with the bulbs themselves, but I'm not sure where to start.
Secondly, a few days later (on the same trip) we lost both the rear brake lights and the rear signal lights. I checked the bulbs and they work fine, but the front signal lights cycle much faster. What's next
Can anybody help me with this?