Welcome Aboard!
The number of channels you can stream should only be limited by the number of tuners available (and in fact if one client is already watching a channel, I think (but haven't tested) you should be able to stream that channel to as many clients as you like without taking up another tuner.
If you are loading the library from the server on your client, you should have the TV guide data and you should be able to choose any channel in the guide and play it.
Is this not occurring?
Let me clarify after a little more testing....
Server 1 with HDHomerun network tuner
Client 1 No tuner
Server - Start off watching ESPN
Client 1 - Start off watching ESPN
Server 1 - Change channel to NBC
Client 1 - Live TV stream Changes to NBC. Client's *display* indicates still watching ESPN (even though on NBC)
Same thing in reverse...
Server 1 - Start off watching ESPN
Client 1 - Start off watching ESPN
Client 1 - Change channel to NBC
Server - Live TV stream changes to NBC. Server's *display* indicates watching ESPN (even though on NBC)
This seems like a bug to me.
As long as I keep server and client on different channels it seems to work as expected:
Server 1 - Start watching NBC
Client 1 - Start watching ESPN
Server 1 - Change to CBS
Client 1 - Stays with ESPN
Not sure what happens if I were to set both client and server back to same live channel, and repeat initial test at this point.
I am a little pressed for time at moment, so this is all the testing I've been able to complete.