i cant realy say if eva is cheaper than fiberglass (its close to the same) . The eva is much faster for me & that makes it easier to remake pieces when they dont come out right.
As far as cutting goes. I use only utillity knifes as well as exacto knifes. Ive have not tried a hot knife yet. Most of the examples ive seen of cutting with a hot knife look like the edges can get a little ruff. Sharp blades jn a utillity knife just help out on getting those realy clean edges that i want.