What exactly do you mean by "trigger" a field?
Is this what you mean:
If you select Creative Team in field one, the list of projects in field 2 would be the list of projects appropriate for the creative team. If you select the Production Team, the list of projects would be a list appropriate for the production team.
If so, this is called a conditional value list:
First of all thank you! And second, yes and no, that is one way it would work but the ideal is that you have to chose an item from field 1 in order for field 2 to appear, that is what I mean by "trigger".
That said, if using a conditional value list if some we're to try and fill out field 2 before field 1, and trust me someone I work with will, would they be able to choose a value?
You can use a number of strategies to make fields or other layout objects appear/disappear:
They all fall in the category of "cute tricks" but they can be made to work for you.
You can also establish validation rules to help catch user errors.
On your last question. If the first field is empty, chances are that the second field's conditional value list would be empty. They could enter a value by typing if it's a drop down list, but there would be no values to select from in the list. A validation rule can be defined that requires that all values be members of a specified value list--so this would catch a case where a user enters a value not on the list.