Could you please make application lists for server and client in this way:
1) Server have a list of application with all needed information about them
2) Client have it's own list of application from last synchronization with server
3) Client have his unique list of installed applications
4) Client loads newer list of applications, or uses the old one - from last synchronization
5) Client compares both his lists to know what he can update or install
I think it will make client a bit more comfortable to use. And client will have no need to ask about each app, as I think he does now.