You can opt for your IPS/IDS to participate in the CIsco Global Correlation Network. This will send some of your traffic statistics to a centralized location for analysis and policies will be created and distributed to IPS/IDS globally. This includes...

According to Cisco's documentation, it's possible. However, I've never been able to get it to work. Using the ASA as the router in routed mode would accomplish this, too.

As for physical interfaces, yes. You can assign a different VLAN to each interface.

Yes. You can separate each network into a different bridge group. However, at this point, you may be better off using your ASA in routed mode. You'll have more control over internal traffic (i.e. traffic between networks) and your network is more sca...