Cisco WAN :: 6500 - Input / Output Drops

I have this topology in part of my networ:k
 
Cisco7200---Cisco6500---Cisco3560---LAN1
                        |
                 Cisco3560
                        |
                     LAN2
 
All devices are interconected via optical 1Gb/s links. There is no QoS implemented on any device and all VLANs are allowed on all interfaces.
Also all links are trunks (with many VLANs)
 
In LAN1 there was a layer 2 broadcast-storm and 4000packets/s was comming to rest of the network (in one particular VLAN).
 
 1) 7200 with G1 should be able to handle traffic up to 500Mb/s, but a lot of users experienced drops on traffic via 7200.
(CPU load was around 10%).
 
2) Why do I have input drops on 7200 on link toward 6500 if CPU was normal. Broadcast comming to this interfaces were cca 4kpps. But since it's destination is not on router these packets should be rejected on interface controller. Is that right? (7200 doesn't even has dot1q subinterface in that VLAN but since 6500 allow all VLANs on its trunk these packets reach 7200)
 
3) Why do I have output drops on Cisco 6500 (it is here as layer 2 device only)? It is max 160Mb/s in output direction. It has WS6724 card with DFC (there is no oversubscription).. Shouln't 6500 send traffic as fast as interface allows (up to 1Gb/s). Am I righ't?
 
4) After all how coul'd 6500 now if 7200 can't handle these traffic?Output drops should be only seen if QoS is enabled (i.e. shaping), or if there is oversubscription on the linecard?