This addon will require participation from the GM. Many of the features will not work if the character is not the GM.
I have divided the project into 2 separate addons.
Guild Manager -
Will be a full featured addon with the ability to control features guild wide. If the user is not the GM, many abilities will be impaired or disabled.
Guild Member -
Will have the ability to view and add items appropriate to a guild members access as controlled by the GM
The Member addon will be scaled down considerably since it will only be gathering info about itself and sending to a DB master (GM or Officer), while the Manager addon will be maintaining full DB sync and hosting updates.
I have spoken with our GM, and since I am 1st Officer of our guild, I have no problem with the GM items not working for me. The GM would also like to test it for you.
I think a ranking feature would be great as we just added a new rank, and it was a real pain for the GM to have to basically demote and promote everyone to get the new rank in the correct placement. Although we are a small guild, 95% of our members use add-ons on a regular basis. The ones that don't, I believe, would use this one more readily than any other.
Also would like to offer another possibility for a future feature suggested by another person in this forum---I am our bank manager in that I have a toon that has an add-on called GuildBanker. She takes care of guild members' money that they send to the bank for safekeeping in their name. When the time comes and they need their money for a mount or whatever, if they are short, the bank "loans" them enough to get the item or mount. They then repay the bank; the add-on allows for negative amounts under the different guild members. My suggestion, I guess, would be to perhaps incorporate the code from this add-on into your tools package, giving proper credit of course to the author of GuildBanker, and saving yourself a ton of time coding it.