I am very new to all of this (training to race, not riding in general), so I can't answer most of your questions, and take what I have to say with a grain of salt, but it looks to me like you could benefit from a little more variety in your training plan rather than just doing the same thing day after day. Even if you're at an overall low intensity right now some days should still be easier than others. This might help with the boredom factor too (I'm stuck on rollers most of the time so I feel your pain).

I'd also suggest picking up some of the Spinervals DVDs to help with the boredom. I got the 'Aero Base Builder' series for Christmas, and they really seem to help the time pass quickly and keep me focused. Mostly I'm focused on wondering why they are having a spin class in a museum or whatever weird space they're in, but it's working well so far.

Also, where did you get that MHR number from? My understanding is that LTHR is a much better way to set your HR training zones, so you might want to look into that.