One thing to note is that you can't save with the free version of pepakura, so if you change the 2D layout, make some screenshots to find pieces easier later.
For foam, a sharp knife is absolutely necessary (I use a carpet knife and xacto blades that I just sharpen often, they last quite a while that way). Contact Cement is good for glueing foam too as it sticks quite strong (if it's the right kind) and is flexible.