2004 E46 320d, DSC lights

Hey,

Im new and really dont know much about cars and i wanted to see if anyone knows this problem well enough to explain it to me before i go into expensive repairs. I've read some things about the problem but people seem to disagree alot on what the problem is or what could be causing it.

First i'd like to mention (not knowing if its connected in any way) that when i turn on my car there is a red light from the rear passenger light bulb. Now i've checked all the lights and replaced those that needed replacing, brake lights and such, however every time i start the car i get that red light bulb signal, saying there is a problem or a broken bulb.
The strange part is, when i turn on the lights the red bulb indicator goes away. It only stays on as long as i dont turn the actual lights on.

My second problem is when driving the other day i hear the beep that nobody wants to hear and i see the DSC light (the one between speed & rpm meter) plus ((!)) (handbrake) turn orange.
The next day when i started it, it was gone but after a few kms it turned orange again. This happend for a few days. Now, a few days later its on constantly. Winter is coming and there is no way i can drive in snow without the DSC.
I went to a friend that has a general car computer that can read some codes off the car and he said that the computer indicated that there was a problem with pressure sensor 1 (and he's never heard of those breaking down). I went to the shop and a DSC Pressure Sensor is not too expensive, but when reading problems from other people on this forums i've heard that its best to switch out both of them because "one could short out the other", which in turn makes it a little expensive (at least here in Iceland).

Now it wouldnt be a problem to do all this if i knew that this was 100% the problem but some people have reported that cleaning some other sensor could be the problem? Or even the control box unit for the dsc? Im not quite sure of all the car part names, like i pointed out earlier im not too much into car repairs myself and my english isnt 100% so my understanding isnt top notch.

So my question is, should i switch out both of the DSC sensors or just one? Should i check something else out first to make sure that the problem is actually in the sensors?
And finally does anyone know what the problem with my red tail light bulb warning could be?

Sorry for the long post, i just wanted to pump out as many details as i could.