It's not you that's confused - it's bmi.

All fares earn miles (in fairness, it tells you this if you click on the "more about..." when choosing your fare on the website). So it makes no difference to your decision, regardless of whether you are crediting to Mileage Plus or Diamante Club.

And yes, you can use your vouchers. Should have the business cabin to yourself.

In my experience, H credits at x0.5 - exactly as it should according to the earnings tables table. The silly names on the fare basis ("baby", "tiny", "arthur", "martha") are irrelevant, as far as I can tell. At worst, you'll get x0.25.

What on earth are you doing in Glasgow?