Hi Scott,
This is a good question that seems to pop up quite often. Of course, up to CCM 5.x licensing is really honor based so there is no report that you can query that will give you this info. Have a look at the following threads that go over this in some detail. Sankar really explains this very well!
http://forum.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Unified%20Communications%20and%20Video&topic=IP%20Telephony&CommCmd=MB%3Fcmd%3Dpass_through%26location%3Doutline%40%5E1%40%40.1ddc3dcb/0#selected_message
http://forum.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Unified%20Communications%20and%20Video&topic=IP%20Telephony&CommCmd=MB%3Fcmd%3Dpass_through%26location%3Doutline%40%5E1%40%40.1ddc57b7
If you wanted to estimate the applicable DLU's as they would apply in the CCM 5.X train you could query your set types and multiply by the appropriate model/DLU number.
Here is the DLU breakdown;
Cisco Unified IP Phone 7902G = 1
Cisco Unified IP Phone 7905G = 2
Cisco Unified IP Phone 7911G = 3
Cisco Unified IP Phone 7912G = 3
Cisco Unified Wireless IP Phone 7920 (no battery) = 4
Cisco Unified IP Conference Station 7936 = 3
Cisco Unified IP Phone 7940G = 4
Cisco Unified IP Phone 7941G = 4
Cisco Unified IP Phone 7941G-GE = 4
Cisco Unified IP Phone 7960G = 4
Cisco Unified IP Phone 7961G = 4
Cisco Unified IP Phone 7961G-GE = 4
Cisco Unified IP Phone 7970G = 5
Cisco Unified IP Phone 7971G = 5
Cisco Unified IP Phone 7985G = 6
Third-party SIP device (basic) = 3 (third-party)
Third-party SIP device (advanced) = 6 (third-party
From this doc;
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_qanda_item0900aecd805009fc.shtml
For question number 2;
Here is a good pre- CCM 5.x Q & A;
Q. Do I need a license for a Cisco IP Phone, and how does the licensing scheme work?
A. Customers of the Cisco CallManager software are required to purchase a CallManager Client Access License (CAL) for each IP phone, SoftPhone, or other endpoint device or application (IP phone) that registers with the CallManager software. This CAL requisite applies regardless of the source (Cisco or a third party) or the functionality of that IP phone.
Customers who purchase a spare IP phone need not purchase a CAL for that spare if that spare is used to replace another IP phone for which a CAL has already been paid.
Note: That spare phone is never registered with a Cisco CallManager until the phone that the spare replaces has been deregistered with that CallManager.
If the spare IP phone is not used as a replacement for an IP phone for which a CAL has already been paid, the customer must purchase a CAL for that spare. The Cisco CallManager CAL policy is that customers must purchase a matching number of IP phones and associated CALs, with the exception of spares that are used as replacements.
http://www.cisco.com/en/US/products/hw/phones/ps379/products_qanda_item09186a00800a6763.shtml#q37
Hope this helps!
Rob
