So I know about the 4 rubber pads on the sides of the car. They make really stable points for my jack stands. Problem is getting my jack stands under the pads if I'm using them to prop up the car. The other issue is that my 2 ton jack only has enough clearance to prop the jack stands under it. I have used a friends 4 ton jack before and was able to do 2 at a time on the front but I was still at a loss for where to place the jack toward the back of the car. Diagrams and pictures a plus.
The e46 has a central jack point in the middle/front of the car, between the front wheels (red circle). Just make sure you use a block of wood between the jack and jack pad to help distribute the force a little.
Use ramps for the rear. Put 2 blocks of wood behind the front wheels, so when you back up on the rear ramps, the front wheels will be on top of the wood blocks. The front will be high enough to jack the center, and then put jack stands under the 2 front jack points.
All BMWs have basically the same lift point locations. On an E46, there are the pads or you can use the seam that has two slot around it right by where the pad would sit. This picture depicts where you should lift the car. You can use other points, but at a dealer they only use these four.
You have an answer for the front... My car is a 2000 E46. Just forward of the differential, there is a steel "band" around the drive shaft. Pretty sizable, and has a flat area on the bottom. I dont know about your car, but I use that to get the rear off the ground. I get the front up first ( the center jack point on mine is a little different that shown above, but similar, it shows beneath the bottom cover ) and on stands, then the back. If you raise just the rear of the car, be sure to chock the front wheels.