What if they miss their first save and they're dead?[/QUOTE
If the entire party misses their first saves, then yes, they are dead. If they are low level, then that is simply the fate of many low level adventurers. If they are high elvel, it is quite possible that they have allies that can ensure that the death is not permanent.
If a DM arranges an ambush such that the entire party can be wiped out by a few failed saves, then he either needs to be prepared to end the campaign or have a way out for the party.
4) You used your party as a barometer.
Please.
Don't do that. It's insulting to some people.
I'm sorry if you are offended. However, even without using my party (the only party I have to show as an example) you can look over the spell lists and class abilities yourself to find many varied ways of escaping a battle that is against you. I listed many of them earlier, but low level versions of escape routes exist as well: Sanctuary saves the cleric, Expeditious Retreat the wizard, Obscuring Mist could save the entire party, rogues can run and hide, monks can simply run, etc.