I agree on the alternating days if you can, especially if you are doing 45 minutes of cardio after weights. I tried to do both on the same days to save time (and not have to go to the gym EVERY day), but on days I did both I ended up starving and ravenous, and usually ended up eating a couple hundred more calories on those days anyway. Killing myself for nothing. When I started alternating (upon the suggestion of all the ladies here

) I noticed a big difference.
As far as the stall on your weight loss, how long has it been? And are you still hitting your target heart rate while on the treadmill? For me over the last couple of weeks, I've had to change my speed and incline to get to the same heart rate, because my body has gotten used to the exercise. Does the machine you use have a "random" or "hill" setting? Try changing it up a little, or use a different machine like an ellyptical or exercise bike just to break up your routine. I was also disappointed in my scale, but I did go down a clothing size recently without losing any weight-so check your measurements, too, before you get too discouraged. The old "muscle weighs more than fat" saying really is true, and a trainer at my gym told me that some people actually gain or don't lose any weight for a while when starting a program that includes weight training, but you should lose inches, which in my opinion are just as wonderful.
As far as what machines to use to speed up your loss, I don't know what you are already using-but my gym has circuit training set up, to work all muscle groups. The more muscle you build/tone, the higher your metabolism will be. I don't think any particular muscle work will make you lose more or less weight, the thing is to aim for all over improvement.