Re the intervals: yes, they help. I had never done structured intervals until this last winter, on the trainer. And I did notice the improvement once on the road. Doing this on the trainer means, for me, that you can do them with reckless intensity, really push to see how far you can go. The worst that can happen is that you have to stop and get off the bike (in your home).

My cadence is a little over 80, sometimes 90+. I'm working my way up, gradually.

@CyborgQueen: the videos I like for the trainer are from the Sufferfest.