The umbrella LLC and each individual series under the umbrella are treated as separate entities, so do I need to get a different tax ID number for each series I open as well as the separate tax ID number for the umbrella LLC?

Umbrella policy is simpler and cheaper.Let's say you set up two LLCs.

Make sure you have Umbrella Policy as well.

Get an umbrella that covers all your assets; and cash value on the property-they asked me for that number.

I am a fan of a good umbrella policy.  

We're in the process of renewing our insurance policies on our apartment and commercial properties throughout Florida, and I'm being told to expect 15% increases across the board for property, liability, crime, etc. and likely larger increases (several hundred percent) on the umbrella policies.

I've reached out for quotes on flood and standard home-owner insurance that the mortgage company is asking for, but I'm thinking about getting an umbrella coverage or similar to cover the rental business.  

I, and my partner, always have umbrella coverage on top of our property insurance.

@Duncan TaylorObviously it is a very personal decision when you decide to switch from "just get an umbrella policy" to "I want to spend 5 grand having a lawyer set up some trusts for my massive wealth."

I've not heard that term.Typically with umbrella policies, you can add in however many properties into the same umbrella that you want to.