About your default name problem, but maybe I misunderstood what exactly the problem is:
You can just do the same with the default name as you did with other variables like magic, by typing a default name inside the quotation marks instead of leaving them empty. For example:
(set: $firstname to "Alix")(set: $lastname to "Dalton")
You can also have a default text displayed in the text input boxes by writing it in the quotation marks of the value segment. That will not yet set the variable to the displayed text though. That only happens upon executing the confirm button:
<input class="box" type="text" name="firstname" value="Alix">