I don't know if you want "an old lady's" perspective, but NoLeafClover pretty much agreed with YOU and I agree with HIM.
When I was in the process of losing my 70 lbs, at a certain point I added weight-training. I did NOT stall weight loss, nor did I temporarily GAIN weight. I cringe when people say that they do.... Weight-training is absolutely essential.
GO FOR IT!
Weight training has the benefit of raising your metabolism for a longer term than cardio. Cardio is great as long as you can keep it up, but the minute you start cutting down, the pounds come right back. When you do weights, your muscles need energy to regenerate for a day or two after, and as you build muscle, your caloric requirements rise as well (since it takes more calories to sustain a pound of muscle than a pound of fat.) So in general, yes, for a healthy lifestyle it is beneficial to work on both weights and cardio, especially when a high percentage of your weight is body fat. Doing weights only every other day is fine, and recommended, or alternating muscle groups between days, so your muscles have time to regenerate between sessions.
In general, you don't lose muscle, it stays with you. when you're working off the pounds, what you're losing is fat, and as long as you're doing it by exercise and not starvation you're likely gaining some in the process. The ultimate goal is to gain a few pounds of muscle while you lose several pounds of fat, and it makes it easier to keep the weight off.