Hi. 

I've  project where my elgg shoudl be customized as follow.
1) GroupFee: The creation of 1 gorup is free but more then one should be by paypal with a specific tabel
2) Members invited in a group can only see and reply what the aministrator create
3) The first page after login is the preferred group.

theese are the main issus but I've other point.

Thanks