a. i think only option 66/150 can be configured. You can easily do this on IOS router or any third party DHCP server.
b. I dont have a sample output but if you go to CLI, there is a command "show network dhcp eth0". This might show some valuable output regarding leases.
c.No idea about this, but if i find out i will let you know.
Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus