No, you can only bed Tali if you already bedded her in ME2. Her being dead would disqualify that possibility. Unless you're some sort of sicko.
I was a good boy in Mass Effect 2 and everybody survived the Suicide Mission even most of the Normandy's jobber Cerebis crew. Now I wish I let most of em die.
The Quarian female Admiral does have a sexy voice. She's from 24.
This is something from the Mass Effect Wiki Trivia Page on Romance which explains what happens.
There is a glitch in Mass Effect 3, where if you are continuing a relationship with Tali from Mass Effect 2 only for her to die during the battle to retake Rannoch, she will still appear to you before the assault on the Cerberus base as though she had survived.(