You asked a question about whether to do weights or cardio first... well, there are a lot of differing opinions on that, and it has more to do with what your specific goals are than anything else.
Generally- I do my endurance/cardio exercises and heavy strength training on different days. However, if I do a run on a weight lifting day, I do the weights first. For me, it's easier to lift heavy weights when my muscles are fresh. I have been a runner for a long long time, I can run on tired legs, sore legs, achey legs... doesn't matter. I lift first because I know I can still get an effective cardio session in after. Also, since weightlifting depletes glycogen stores, my body has to resort to burning other fuel during my run.
If your goal is to build endurance or improve cardiovascular health, it might be beneficial for you to do cardio first, while you're fresh, and do weights after.
Another approahc entireley is something like circuit or interval training... you have short, intense bursts that are anaerobic, with aerobic activity in between. You don't have to keep your heartrate crazy high, but you never really fully recover, like you would between weightlifting sets.
Note, this is just my opinion, what works for me, and what I've read in various articles. If other knotties have any advice one way or the other, or can find any articles from reputable sources, please post!