Will cycling 1 hr a day, 5x a week really help me lose weight?!

Of course it will help, but how effective it will be depends.
Are you starting cycling in place of another exercise or are you starting from having done no exercise? Will you be using a cycling machine, or actually going out and riding a bike, and if so, where will you be doing it?
Weight loss is all about how many calories you burn, versus how many you take in. As long as you burn more than you eat, you will lose weight. (So you can't eat nothing but McDonals, and hope that exercise will make a huge impact. Gotta eat healthier too.)
If you're changing exercise types, cycling might not make that much of a difference, but if you didn't exercise at all before it will make a big difference. The harder you ride, the more calories you will burn as well. So riding up hills, or riding faster or harder, will have more of an effect than simply riding on level ground. Exercise bikes have programmed courses in them, but if you're actually riding outside you will need to carefully choose where you ride. If you haven't been exercising, then start with an easier ride and work your way up to a harder one, or else you will exhaust yourself.

Not really something we could possibly answer. It depends on the intensity of your cycling, your current weight and height, as well as what you're eating.

Just cycling alone won't do a whole lot if you aren't on a proper diet. You also need to do more than just cardio exercising like cycling in order to tone up your body.

Cycling alone won't do it but it can help. You have to cut down on how much you eat cut down, but don't eliminate starches, eat more fresh fruit and vegetable. No snacking between meals, cut out all sugary soft drinks. The fast you cycle the more energy you use the more calories you will burn.

Try 30 minutes a day, 7 days a week. And eat a very well balanced and healthy meal.