I definitely agree with Tom here. Mixing up your routes and training methods is the best (and most interesting!) way to reach your goals. The long rides have their place, but doing them as your only method of training would get pretty drab after a while. Those rolling hills you have are a great way do a type of interval training - it sounds very similar to what I ride in all the time. And by the way, there is nothing wrong with going above 60% HR - you just want to make sure you give yourself some easy pedaling for a while afterwards, then go ahead and do it again!
And congrats on the weight loss! That is a fine accomplishment! Keep it up!