Good questions, and I think it is attempted on most projects. You can check out the status of the projects yourself e.g. by checking the issues on Github.
Here are some of your answers I’ve digged up for you deeply buried for non-developers:
We do have contact with the Mycelium developer, see: https://github.com/FuzzyBearBTC/android-peercoinwallet/issues/13
Fuzzybear reached out to the Armory developer, but not sure if that has been established: https://github.com/FuzzyBearBTC/PeercoinArmory/issues/5
We also have contact with the Omniwallet developers (Mastercoin) and the Peercoin developer (Sunnyking) 
I think having a community repository is a good idea. We could prepare and test code, and make clean pull requests to the official repository when the community is satisfied with the changes.
We must be very careful not to fork the blockchain though. We should not make any change to the protocol itself (or only in isolated branches we never package).
Putting the repository in a community group looks goods to me.
About the official repository donations, if Sunny King is willing to add a collaborator from the community, we could decide the reward of each commit (see http://www.peercointalk.org/index.php?topic=2531).
Updated the original post with the latest status of the donations.
Just bringing the following into the lights:
Some people are working on the Omniwallet project but waiting for some further developments by the original developers. So this is still in its early stages
But…
Not open source, but being the first with a Peercoin web wallet is bkchain.
See his announcement thread here: http://www.peercointalk.org/index.php?topic=2517.0
I think this is a great developments and enables the use of peercoins on mobile devices and with that payments at point of sale.
You might appreciate his contribution by donating to his address at the bottom of his site: http://bkchain.org/ppc