Hi I would like to create my something like a t shirt designer form, but I wanted the ability to create multiple lines so that I could also provide other templates for my clients to customize, such as business cards, postcards. Is the form building good for that? How about the cropping tool, rotate and scaling tool? Would I be able to include that on my interface? If not could you please tell me what other plugins I might need to accomplish that? I would like to have configurable products as well, maybe a calculator to calculator area (footage).

A lot of the features you are asking about aren't built into the form builder. There are numerous scripts out there for designing t-shirts that would probably fit your needs better. If your dead set on the using the form builder and you know php and javascript , I would take a look at fabric.js. It's a fully customizable canvas script that you could wrap in a form.