BK - Why are you suggesting a 6hr limit? I'd suggest it's time on feet rather than distance.
How many B2B are you planning as you mention this is your first?
Martin - 10 hours on your feet a day?? That's all the training you need! Agree that some walkers are faster than runners - I do what I call a grandad shuffle when I'm tired and I still can't catch some walkers. If you've already done Comrades, then I can't see a problem for you. Great race plan by your friend by the sound of it.
Your target of just finishing is a good one martin. I'm not sure what happened at TP this year (I marshalled at the finish line), but there seemed to be a large drop out rate. Whether this was because it was warmer in the day and then a temperature drop at night than expected, or whether some of the runners thought just because it was flat it should be an "easier" 100 I don't know (and I'd welcome their opinions).
I hope to be doing it next year, but the fact that it is so flat, you are using the same muscle groups the whole way and there's no hills for a walk break etc so it's not easy.
Carter - usually if there's a compulsory kit list, it's for a good reason - I'm guessing the Peaks' weather can change rapidly. You can get micro fleece gloves and hat which weigh almost nothing, so they shouldn't really be a problem.
I'll echo C-BtbM's comment regarding shoes - can't help you there, only you know what's comfortable. But if the Race Organisers are worth their salt, then you should be able to contact them and they will answer your questions.