Cutting the Unit Square into Rational-sided Pieces

This post continues this old thread and this recent post here. The immediate trigger was an email exchange with Dirk Frettloh (Thanks!)

The following questions seem related to the still open question whether there is a point(s) whose distances from the 4 corners of a unit square are all rational.

1. To cut a unit square into n, a finite number of triangles with all sides of rational length. For which values of n can it be done if at all?

2. To cut a unit square into n right triangles with all sides of rational length. For which values of n can it be done if at all?

3.To cut a unit sauare into n isosceles triangles all sides of rational length. For which values of n can it be done if at all?

Now, one can add the requirement of mutual non-congruence of all pieces to all these questions. And one can add rationality of area of pieces etc... and so on...