This is a good discussion. A couple things to add:
>> I really want to pedal 70 or more pounds off.
Forget it. Not how it works... the (calories expended) - (calories eaten) math is not how you lose weight, unless you go starvation level.
But: your body works so much better when you exercise that you will find it easier to lose weight. Much of it is about what foods you eat. Lose the simple carbs and the highly processed foods. And find out what works for you. I just spent ten days at my parent's house, ate like a pig, drank beer every night (they made me!), exercised little -- a couple 10 km bike rides, daily walks -- and lost a few pounds. Biggest difference to what I do at home: no not much food at night, we ate the big meal at noon. Your mileage will vary; figure out what works for you.. .
The other thing I want to mention is comfort. I used to ride a lot from my mid-20s to early 30s. Always for transportation, the occasional loaded tour, and a longer ride here and there, nothing organized, 2,000-plus miles a year. I was in great shape and loved riding. Then the grown-up job, the house, the kid... I still rode a bit and went on an annual tour, but it got harder and it often was uncomfortable and I'd count down the miles. Not a good thing.
For the last couple years, I started riding a lot more regularly; a lot of 15- to 25-milers, some of them against the clock, and it took four or five months to reach the comfort level I used to have -- where you're tired, so you take it easy to roll the final five miles home -- and you're comfortable. That is really important. If you can just go left pedal - right pedal and let your mind wander, and you're not worried about a stiff neck or chafing, that's when you're a cyclist.
From there you can build, or you just keep riding at 14 mph, but it's a great place to be. And if you keep riding, you'll get there. Good luck!
cheers -mathias