BA and Razors, why?

Could any experience BA player or anyone who knows about this tactic (RB/5RAS) to explain the reasoning behind this kind of play? I understand they have protection now instead of Jump packing around cover and they can move 18" instead now...but here are the questions I have about these sort of Mech lists:

*Sorry that there are so many questions, it's just I really think these lists look cool and would like to know more about them before I invest in buying all these RB's.*

1) Is there a reason to only field 5x RAS (regular assault squad) in the RB's? Why don't they go in 10s so you can have 2 Meltas or something per RB?

2) Some lists do a SGT with Power Fist in each RB and others go Melta and others do Flamers. What's the best way to equip these 5 man RAS units?

3) Why upgrade the RB's with TL-something? @ 11 armor sides and front theyll pretty much get shot down really fast then

4) With all these small squads how do you use them efficiently...Do you move all your RBs to the same location and swarm people with the RAS guys in 2-3 RBs? If you spread out your guys will only be attacking in groups of 5...

5) Why do most of these lists not have any Sang Priests? I've played with 10 man RAS units + Sang Priests and Sang Priests seem to give so much more to RAS units strengths.

6) Those experience with fighting or playing with this list what is the best heavy support/ fire support for them? Devastators? I have 1 Baal Pred right now and 1 Reg Pred. I'm thinking of convering the Reg Pred to a Baal and using 2x Baal Preds with TLAC + HB sponsoons.

7) Are RAS units + your support fire (Baals/Devs) enough? Almost none of these lists have any Elites anywhere. Some run 1 Dreadnaught or so but why nothing else? Terminators in LR, DC in RBs?

8) Last question I think... How do these lists cover objectives with no truely great range in the small 5 man RAS units. Swap in some Sniper Scouts or what?


Whoever helps me out thank you so much for your time. I know it's a lot of questions! >_<