I agree with all that was posted above me and have a few comments that might be helpfull.
I do agree with passing on loot to spread it around, the biggest upgrade is upgrading the overall raid rather than one player, since in the larger raids you are only as strong as your weekest link. aka someone standing in fire, gettin hit by random aoes or not putting out enough dps etc.. My only issue is where rebel states that people we will or could be brought in for specific gear or bosses, I feel like this can be an issue.. This will change group synergy and overall awerness, the idea of this 1 MAIN group was to power through the shit bosses and kill LK that being said we need to focus in on that.. if that is truely the guild goal. Using the same 30 people or so for each fight will keep people on the same page and you can know what to expect from your fellow raiders aka i know rebel will be in this place at this time.. or cyianna likes to heal this fight this way etc..
my advice from raiding since wow first came out aka filling and managing 40man raids is to assign officers for specific roles beside the typical officer/guild decisions.. for instance decide on a raid comp that makes the most sense for the raid, and assign an officer to each "type" and create a core group and then have a set amount of back ups.
for instance:
core:
2-3 tanks - pryiadin
5-6 heals - cyianna
6-8 mele - rebel
6-8 ranged - gump
before each raid invites the officers invite the raid role they are assigned too, this allows for a little flex, as well as allowing a specific officer to monitor the individual groups raid than the whole raid. This would also allow the 30 or so guild memebers to know where they are in the guild ranking. I believe it should be predeterminded that these are our top 30 raiders and will get invites each week to progress and kill LK these are our 10-15 alt raiders and will get an invite if a top raider cannot come for whatever reason. Let me also say as rebel and gump have stated top or alt does not refer to anything but a raid spot not how good a player is, as they stated there should be amny qualities that determine who gets these spots. It would be very short sighted to try and assume everyone will get into this core raid etc the numbers just dont allow it.. 40-50 or so active raiders can't fit into a 25man raid.
Sry for the long post just some ideas and my comments on things.