You can create the textfield and set many of its parameters with one line of code:
this.createTextField("my_txt", 1, 100, 100, 300, 100);
The code above creates a text field named my_txt with a depth of 1, x coord of 1, y coord of 100, width of 300px and height of 100px. It would be a dynamic text field by default.
The code below should help in this case.
b1.butText.buttonText._width=130;
b1.butText.buttonText._height=40;
b1.butText.buttonText.font=arial;
Size 12 font is the default.