Here's the deal, as it's been told to me on insurance..
It's not like car insurance... basically, they're supposed to operate on a standard percentage of your budget...
This is why many production houses, in both film and video, budget the standard rate into their production budgets... I'll have to check on my numbers, but I believe it's around 10 to 12 percent.
As far as premiums go... I'm currently under the impression that it's a flat rate type of situation.
As far as being new... or just out of school... it's more about wether you have the money or not... they wont insure you for free... but if you have the money, how can they say no...
Also, when you're in school... there is some measure of insurance that the school should already have... though I'm sure that vary's from school to school.
Insurance is important...
once you've acquired insurance for a film... you'll be able to recieve lower rates on gear rentals... which can save you money in the long run.