Brake Warning Light Flashing / Maybe Related to Other Issues?

This morning while driving the red brake warning light began to flash along with the customary audible beep.
The ABS light did not come on (assuming there is one). Braking power seems to be normal as we have not noticed a softening of the brakes in any way. I have not checked brake fluid in the master cylinder but will do that. A few other things to note. Maybe related / maybe not.

1) The rear brake lights (lower bank) do not come on when braking. Also the cruise control does not work. I was planning on replacing the brake lights and/or fuse today, when the alarm went off.

2) The cable connecting the emergency brake release lever is broken and so when pulling the lever there is no tension. Was told (we purchased this very recently) not to use the E-brake until the cable was replaced. I believe just the short cable connecting the lever to the longer cable is what is in need of replacing. I've done that myself on other vehicles.

3) The cruise control does not work. The previous owner said it worked normal until one day it just didn't work at all. Looking up info on YouTube I see where the cruise control and brake lights can both be affected at the same time as they connect in a common electrical box under the dash, and that GM was notorious for using a gauge of wire too thin for the braking application, causing the insulation to melt and a short to occur. Replacing that short section of wire and soldering in a higher gauge was recommended.

So there you go. I don't know if this is all interrelated or not, but would like insight as to what you would recommend in order. Thanks!