I'd get a headlight assembly. Also check out RockAuto Auto Parts
for used parts.
brake fluid reservoir should be fairly close to the top. Even with very worn pads AND shoes, the fluid level should not drop more than 1/3" to 1/2" from full. Brake fluid you can fill nearly to the brim and there's no worry of expansion in the reservoir.
If you have rear drums, it'd be worthwhile to pull the wheels off and do an inspection. A lot of people are terrible for not ordering a new spring kit with new shoes. Old parts once removed and reinstalled can add to the fatigue of that part causing failure in 100 miles or 10,000miles+.
With the brake light on, I'd take it to AutoZone and see what codes they can pull for free and go from there. It might be a faulty sensor of sorts too.
I know when I had a wheelbearing go on my Durango (front bearing), the ABS/brake light both came on at different times. For the Durango at least intermittent brake light coming on meant bad speed sensor.