Some Torque 2D graphics questions

I am working with an artist in Torque2D / Torque Game Builder, and he asked some questions that I don't know the answers to right now. These were his questions:

- Is there a frame rate or memory cost for having a lot of textures with alpha channels on screen?

- Is there a way to change the way alphas blend? For example, can "Additive" be used in order to fake some lighting effects?

Thanks for any assistance.