As of late, my oil pressure light has been flashing on and off while braking and only while braking. The last time I drove my car it told me to shut the engine off because oil pressure was too low, but this message too only appeared whenever I was braking. I have already taken my deville to the cadillac dealership and they said that my oil pressure sensor was functioning properly and they said that the low oil pressure message was due to the fact that oil was running low in my car, hence the reason I had my check oil level sensor replaced. The oil in my car was so low due to a small leak in my engine casing (which the technician told me was nothing to worry about, certainly not enough to pay the 1800 dollars to have it fixed). I got my car from the shop today and already the message has began to appear again, this time it's more frequent but it's still under the same circumstances. It was my understanding that the oil pressure light would stay on if there actually was something wrong with the oil pressure, which makes me wonder if it is somehow related to the brakes. Is this possible? If so, what is wrong? (Please be tolerant of me, I don't know mcuh about these sorts of things)

If there is oil in the crank case my guess would be a bad oil pressure sensor. It is located by the oil filter. You can remove it and put a pressure guage on it to confirm whether or not you have pressure. Most likely you do, and if so, it is a bad sensor that needs to be replaced. I am surprised the dealer didn't do that to comfirm what the problem was.
By the way, how low were you on oil? You'd have to be pretty low to cause oil pressure problems.

I was quite low on oil but I would estimate about a half a quart, seeing as how the check oil level warning is supposed to kick in at a quart and a half I felt the need to have it replaced. I don't know what to say about the oil pressure sensor, the technician at the dealership stated that the sensor was working perfectly, but I do find that rather hard to believe myself.

Have the oil pressure switch replaced. It is really hard to check as it can start to wear on the contacts just at the point that the switch engages causing it to be intermittant. It is really not expensive and relatively easy to replace.