We (officers) still need to discuss these ideas/request further before we can make a final decision.
Personally I like your initative and incentive for players who doesn't get to join mythic for the night to still do some raiding.
The fact that "back-up raiders" not getting a spot for the night and feels unmotivated by this is a known issue that is very hard to solve. We discuss continous integration alot and right now we're trying a system with 25 core raiders with some rotation, we'll see how this work, but also this is another topic to discuss.
So, about starting a second raid team. This might be alot of work and require some endurance and patience. I believe that a stable group would only be acquired after consistently keeping these second-group-raids up on a strict schedule where players who sign will get to expect that the raid will happen, even if you need to bring pugs to fill up. If everything goes well then eventually the guild raider portion of the group will be greater or even full, and things will be smoother.
DKP for HC has been removed after unimous decision last meeting, so rewarding this for attendance is out of question as for now.
I really like the "mythic raid start" + 30 minutes suggestion. This way people from the mythic team atleast may consider joining the HC run to help out. To be realistic i think that alot of mythic raiders would not feel like joining for HC, but who knows until we try and see :) I'm just saying that the group will probably consist of lower geared and/or people behind on the current tier progression, but that it is still worth the 30 minute start delay to find out.